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Plowing refers to the phenomenon by which a landslide displaces and pushes the path material forward. Despite its importance in shaping the dynamics of many rapid flow-like loess landslides, the mechanism of plowing is not fully understood. Therefore, this paper presents an improved numerical model based on the material point method (MPM). This model takes into account the interactions between the landslide mass and the path material. The reliability of this model was validated by simulating two granular column collapse experiments involving interaction with an erodible mass. The model was then applied to analyze the plowing dynamics of the Ximiaodian loess landslide in Jingyang County, Shaanxi Province, China. A series of well-designed simulations were conducted to investigate this specific landslide event, contributing to a deeper understanding of the plowing phenomenon in loess landslides. The simulation results show that our model can satisfactorily simulate the plowing process of the Ximiaodian landslide. The plowing process of a rapid-flow loess landslide is proposed to consist of four distinct stages: 1) the collision stage, when the landslide strikes the terrace, resulting in the bending of its strata; 2) the shear failure stage, characterized by significant plastic shear deformation within the bent strata, resulting in the formation of multiple shear failure planes; 3) the steady plowing stage, during which the deformation structure in the affected terrace stabilizes and plowing continues in a steady pattern; and 4) the stopping stage, when the propagation of the disturbed terrace gradually stops. Furthermore, the disturbed terrace zone exhibits three distinct deformation structures. In the rear part, a stable zone develops where the terrace layers are compressed. However, due to the compressive forces exerted by the overlying loess, no significant shear deformation is observed. The middle part is the shear failure zone, characterized by the formation of multiple shear failure planes. The front part is the upheaval zone, where the terrace layers are slightly bent and tilted. • An improved MPM model is proposed to simulate the plowing process of rapid flow-like landslides. • The plowing mechanism of a real loess landslide is analyzed by the MPM model for the first time. • The plowing process of a rapid flow-like loess landslide consists of four stages. • Three distinct deformation structures are formed in the disturbed terrace zone during the plowing process. [ABSTRACT FROM AUTHOR]

Abstract Loess is a meta-stable, cemented assemblage of mainly silt and clay-sized particles of low plasticity. When dry it behaves like a brittle material, but when wetted up the fabric rapidly collapses. Unique geomorphological features include extensive surface erosion, soil piping (loess 'karst'), catastrophic landslides, and widespread collapse (hydro-consolidation). The Chinese Loess Plateau is a more or less continuous drape of thick loess covering some 440,000 km2. It is one of China's regions that is most prone to geohazards. This paper reviews advances in the research related to loess geohazards, drawing particular attention to the need to apply research findings to recent, very large (mega-)construction projects in loess terrain such as the Mountain Excavation and City Construction in Yan'an levelling 78 km2 for urban expansion, the Lanzhou New District creating 246 km2 of new level ground for construction, and large engineered interventions in the landscape for gully control and land reclamation such as those in Shaanxi and Gansu generating agricultural land covering an area of some 8000 km2. These projects are in response to increasing pressures to facilitate expansion of urban centres, their interconnecting infrastructures and their agricultural support systems. It is argued that, where proper application of scientific knowledge for engineering control (e.g. densification, drainage) of these new landscapes is absent, these projects could generate a substantial, and costly geohazard legacy for future generations. [ABSTRACT FROM AUTHOR]

Numerical modeling of landform evolution is the key to understanding the formation of land surfaces. However, landform evolution occurs under certain initial topographic conditions, while existing landform evolution models often use a plane or a randomly produced surface to establish the initial topographic conditions. This misunderstanding of the initial topographic conditions causes the landform evolution results to deviate greatly from the real terrain. Therefore, the initial topographic conditions must be reconstructed and integrated into the current numerical landform evolution model. In this paper, the Loess Plateau of China was selected as a typical sample area. The paleotopography was reconstructed and integrated into the numerical landform evolution model. Based on the evolutionary mechanism of loess landforms, modules of surface erosion, matter diffusion and precipitation were selected to construct a numerical model of loess landform evolution. Moreover, randomly produced terrain was used as the initial conditions during the landform evolution process and compared with the paleotopography-constrained evolution results. In addition, the results of the landform evolution process were evaluated with different terrain factors, and the uncertainty of the model was assessed by comparing different model conditions. The results show that, due to the control of paleotopography, the evolution results can maintain the main morphological structure of valleys in the loess landscape. Without considering the paleotopography, a large difference exists between the evolution results and the true ground terrain. These results show that paleotopography is an important feature of loess landform evolution modeling and is indispensable for reasonably expressing the process of landform evolution. Finally, the numerical modeling of loess landform evolution with the consideration of paleotopography can not only help to achieve a better understanding of the loess landform evolution process but also provide a reference for feature dependent landform evolution modeling in different landform applications. • Paleotopography affects the evolution of loess landform in the Loess Plateau. • We integrate the paleotopography into the numerical loess landform evolution model. • Our results can maintain the main morphological structure of loess landform. • Our research provides a reference for feature-concerned landform evolution modeling. [ABSTRACT FROM AUTHOR]

This paper studied the impact of a gully-type gangue dump in the Daliuta mine area, Shaanxi, China on the groundwater environment and its contamination control. Multiple methods including eco-hydrogeological survey, soil column leaching test, field test and groundwater flow analysis were applied in the study. According to the field survey, the stack of gangue had changed the original feature of groundwater flow system, with the groundwater level of the gangue field raising about 1–3 m compared with the condition before the establishment of gangue dump. The long-term immersion of gangue had released various harmful substance into the groundwater and affected the downstream areas. The leaching test showed that the loess could significantly purify the mine wastewater by increasing pH value from 4.5 to 6.2–6.7 and absorbing heavy metals. Based on the loess column test, two loess permeable reactive barriers (LPRBs) were established in situ to improve the groundwater environment of gangue field. Besides, the vegetation restoration had been successfully carried out by covering a 30 cm-thick loess layer on the coal gangues and planting Alfalfa and Artemisica ordosica to improve the ecological environment, and the vegetation coverage had increased from 10% in 2008 to about 65% in 2013. [ABSTRACT FROM AUTHOR]

Thick loess deposits are considered problematic soils due to their susceptibility to collapse suddenly and in large volumes upon increase of water content. In the past decades, a large number of landslides occurred in the Loess Plateau in Gansu Province, north-western China, triggered by the extensive irrigation. The increase of water content has been identified as a key factor controlling the loess strength. However, the role of long-term saturation and pore fluid chemistry changes has not been investigated systematically. This paper reports on an experimental study on loess samples from Heitai loess terrace (Yongjing, Gansu) carried out through chemical analyses, oedometer and ring shear tests. The natural pore fluid was found to be a concentrated saline solution in unsaturated soil condition. Upon saturation, the pore ion concentration drop can contribute to shear strength loss in the clay component and volume decrease. A prolonged exposure to the irrigation water might facilitate cement dissolution, which could result in further weakening. [ABSTRACT FROM AUTHOR]

Loess collapse is an important factor in earth fissure formation, and earth fissures resulting from loess collapse are widely distributed in loess areas in China. To explore the basic features and formation mechanism of collapsible earth fissures, we conducted an in situ water immersion test in a loess area. This paper describes the genesis of collapsible earth fissures by monitoring the development processes of collapsible settlement and earth fissure formation. This paper demonstrates that the infiltration process can be divided into three stages, and the subsidence curve of the whole test process can be divided into six stages. During the test, the collapsible deformation gradually developed outward, the collapsible settlement decreased with increasing distance from the test pit, and the horizontal influence distance was approximately 18 m. The collapsible earth fissures were parallel to the test pit, and characterised by horizontal tension and vertical dislocation. With the collapsible deformation expanding outwards, the location of the earth fissure developed outwards. The tensile stress and tensile strain caused by the differential collapsible deformation caused the formation of collapsible earth fissures. When the tensile strain or tensile stress was greater than the ultimate tensile strain or tensile strength, the loess experienced tensile failure and formed an earth fissure. • Collapsible subsidence section showed symmetry, forming a "U" shape. • Collapsible earth fissures are characterized by horizontal tension and vertical dislocation. • Tensile stress and tensile strain are main factors for collapsible earth fissures formation. [ABSTRACT FROM AUTHOR]

Bed entrainment plays an important role in the run-out process of a flow-like landslide. A limited number of studies have investigated the influence of entraining loose materials on the mechanical properties of a landslide, and some of them have considered bed entrainment either by mechanical or empirical methods. In this paper, a modified finite difference model was used to analyze the propagation process of a typical flow-like landslide with bed entrainment that occurred in the Jingyang loess tableland, China. In this model, the mechanical parameters of the sliding mass were modified according to the local entrainment depth. Triaxial Consolidated Undrained (CU) tests and ring shear tests were conducted to obtain the mechanical parameters needed in the numerical simulation. The triaxial CU tests were conducted on three intact loess samples taken at the back scarp of the landslide, and the ring tests were conducted on gravelly sand samples taken from the first terrace of the Jinghe River, which includes the landslide deposit. The results show that both the simulated run-out distance and final covering area agreed well with the field data. The modified model revealed the propagation process of this landslide. A major contribution of this study is that entraining the saturated gravelly sand contributed to the flow-like movement of the landslide. The case study investigated here is helpful for better an understanding of the flow-like transformation mechanism. In addition, the numerical model adopted in this paper can be effectively used to assess or predict the propagation processes of similar landslides. • The propagation process of a loess flow-like landslide with bed entrainment is analyzed. • The significant shear strength loss of loess contributes to the rapid acceleration of this landslide. • Entraining saturated terrace material contributes to the flow-like transformation of this landslide. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on eleven loess soils retrieved from NW China to explore the influence of grading and age on soil mechanics. There are overall consistent characteristics in stress-strain relationship and stress paths for the loess tested though detailed property depends on the combination of v i and p 0 '. The critical state parameters are quantitatively analyzed against the soil properties. The critic state line (CSL) in p ' − q plane is less variable. The M value of specimens tested varies from 1.15 to 1.41 and the corresponding φ cs ' is between 28.8° and 34.8°, which is not clearly related to the loess grading and plasticity index. In the volumetric plane, the intercept Γ of CSLs varies from 1.63 to 2.17 and the gradient λ of loess fall within a narrow range of λ = 0.08 ± 0.03. The λ linearly increases with the increasing plasticity index I p. The intercept Γ and gradient λ against grading indices has an overall liner trend, i.e., decrease with the increase of D 50 and increase with the increasing C u and C c values. The intact loess usually has a higher I B value, roughly between 0.5 and 0.9, indicating a relatively high liquefaction potential. • The detailed shearing behaviour of loess specimens depends on the combination of v i and p 0 '. • The plasticity index and particle gradation parameters of loess do not appear to significantly affect the M value. • The intercept Γ and gradient λ of CSL against grading indices has an overall liner trend. • The intact loess generally has a higher liquefaction potential. [ABSTRACT FROM AUTHOR]

Undrained shear behavior of loess after the K 0 consolidation was investigated through laboratory experiments. Both the monotonic and cyclic triaxial tests were performed on the intact loess samples retrieved from a construction site in Yan'an city, China. It was found that the coefficient of lateral earth pressure at rest (K 0) of the intact loess is stress-dependent, and it varies between 0.46 and 0.85. Under the monotonic loading condition, the peak q in the undrained shear test is higher for the samples under the K 0 consolidation than those under the isotropic consolidation. Besides, the cyclic loading tests were conducted on the loess samples subjected to different magnitudes of the initial deviatoric stress, including the K 0 stress state. The test results revealed that different initial stress conditions cause distinctly different failure patterns. It includes the cyclic mobility with progressive development of the axial strain, and limited deformation followed by an abrupt gain of the axial strain with no precursor. In accordance to the build-up of the excess pore water pressure during the tests, each failure pattern of loess was interpreted in the q - p ' diagram alongside the undrained instability state (UIS) line. The outcomes of this paper suggest a pressing need to thoroughly consider the K 0 values of the intact loess with variations of the initial stress state. • K 0 value of intact loess samples is stress dependent. • Shear strength of loess is underestimated if K 0 stress state is not properly considered. • At no stress reversal condition, an abrupt failure of loess sample can take place. [ABSTRACT FROM AUTHOR]

Shallow loess landslide induced by rainfall is a widespread form of slope failure on the Loess Plateau of China. The hydrological response, evolutionary mechanism and failure processes of unsaturated loess slopes under precipitation in a field scale are currently lacking. Three groups of full-scale field experiments with different rainfall intensities were conducted in Jingyang County, Northwest China. Instrumentations including soil moisture sensors, tensiometers and earth pressure cells were installed in the slope. This paper presents the results from three types of sensors to reveal the surface infiltration process and deformation characteristics of unsaturated loess slopes. In addition, SEEP/W and SLOPE/W were selected to quantify the effects of soil suction strength on the stability of the homogeneous loess slope. The results show that the maximum infiltration depth of homogeneous loess slope after two days of continuous heavy rainfall is about 0.6 m. The infiltration depth and seepage velocity on the slope crest and slope toe are faster than the middle of the slope; The decrease amplitude and decrease speed of matric suction increase with the increase of rainfall intensity. Moreover, it is found that the rainfall intensity only affect the development of slope deformation and failure in terms of the time scale, but has little influence on the failure mode; Tensile cracks at the slope shoulder develope more rapidly due to the creep deformation of slope, the deformation and failure at the slope shoulder are the key factors controlling the occurrence of loess landslides. In addition, the proportion of suction strength in shear strength is limited, and the finiteness of the suction strength determines that its attenuation will not determine the stability of homogeneous loess slope without preferential infiltration channels. However, the increase of positive pore water pressure at the potential slide surface may be the key factor to determine the slope failure. • We used field experiments to quantify the relationship between rainfall infiltration and loess slope stability. • The infiltration depth and seepage velocity on the slope crest and slope toe were faster than the middle of the slope. • Cracks at the slope shoulder were the key factor controlling the slope failure. • Quantify the effects of suction strength on the stability of homogeneous loess slope. [ABSTRACT FROM AUTHOR]

Abstract: Geological burial and landfill have been widely practiced for disposal of nuclear wastes. However, radionuclides in the waste leachate from landfill facilities can contaminate soil and groundwater. Chinese loess is widely distributed in China and has been involved in large-scale disposal of nuclear wastes. Consequently, there has been an urgent need for understanding and predicting the fate and transport of contaminants in both vadose and saturated zones in the loess. In this paper, the distribution coefficient (K d ) values of Strontium between a Chinese loess and groundwater were determined in batch experiments. The isotherm could be described with nearly linear isotherm model, which resulted in a K d value of 40.0 cm3/g. Based on this K d value, the retardation factor (R d , the ratio of pore water velocity to solute transport velocity) value was calculated to be 112.6. As an alternative approach, the R d value was also determined through independent column experiments and transport modeling. Bromide (Br−) was used as a non-reactive tracer, and reagent SrCl2 was used as a surrogate for the radioactive isotope (99Sr) in the experiment because they share the same adsorption and transportation characteristics. An equilibrium-based model and a two-region non-equilibrium model were employed to interpret the column sorption data of Sr. The computer program, CXTFIT 2.1, was used to estimate the parameters by simulating the breakthrough and retention curves of Br and Sr, respectively. The resultant D (dispersion coefficient) value for Sr transport was much lower than that of Br−, indicating the important effect of chemical non-equilibrium of Sr in the loess system. The observed Sr retention curves in the loess were best modeled by the two-site transport model. The R d value determined from batch equilibrium tests differed markedly from that determined from the column transport experiments, and the R d value decreased with increasing pore-water velocity. The relationship between D and pore water flow velocity (v) was determined as a D = 1.192v 1.26. The results from this work indicate that the strong flow and non-equilibrium effects on the transport parameters (R d and D) must be taken into account in Sr transport modeling. [Copyright &y& Elsevier]

Abstract: For the Xiashu loess–palaeosol sequence in Nanjing, China, further to our work on the cyclic variability in its chemical composition and swelling-shrinkage properties [Xia, J., Huang, G.L., Liu, Z. T., Chen, X.M., 2007. Cyclic variability in chemical composition and swelling–shrinkage properties of the Xiashu loess stratum near Nanjing, China. Pedosphere 17 (5), 666–672.], this paper studies the cyclic variability in its microstructure and physico-mechanical properties and the corresponding influence on its engineering behaviour for geotechnical and geological practices. In addition, the cyclic variability in the soil''s grain-size distribution and geochemical characteristics is compared with that of the loess–palaeosol sequences at two other sites in China, indicating a geographical pattern of cyclic variation of the sequences. [Copyright &y& Elsevier]

Abstract: This paper contributes to a better understanding of the source of dust storms in northern China and the relationship between these sources and other aeolian sediments in this region. Sediment samples in potential source areas were collected from the Hunshandake Sandy Land, Heaven Desert, the loess deposits of the Bashang area, the mountainous basins and valleys north of Beijing and from the Badain Jaran Desert and Hulunbaier Sandy Land (). Dust samples were collected in Beijing during two dust storms in March 2002 and April 2006. The laboratory methods used in this study included measurements of abundance of trace elements, in particular the rare earth elements (REEs), mineral assemblages and grain size. The REE contents, Eu and Ce anomalies show clear differences between various deposits. Provenance is considered to be the key factor influencing REE patterns in the study areas. The REE abundances and patterns indicate that the aeolian sand north of Beijing, such as in the Heaven Desert, is mainly of local origin rather than from desert encroachment from the north. The mineral grains carried in dust storms, however, are highly mixed, and may come partly from local sources but mainly from distant desert regions in western China. [Copyright &y& Elsevier]

Abstract: The Taiyuan Graben and the Linfen Graben are two fault-controlled grabens in the Fen River basin, north China. Broad paleolakes periodically occupied the two grabens during the Pleistocene. This paper discusses how neotectonic activities and paleoclimate changes may have influenced the development of the paleolakes in the two grabens during the middle to late Quaternary, based on the lacustrine landforms and sediments. The distribution of lake terraces and their correlation with loess/paleosol series indicate that three paleolake regressions with vertical drops of about 40–60 m occurred in the two grabens at about 0.76 Ma B.P., 0.55 Ma B.P. and 0.13 Ma B.P. Analysis of the factors controlling paleolake development suggests that rapid tectonic uplift may be the main cause of the three paleolake regressions. Changes in the facies of the lacustrine sediment also suggest that, when tectonic movements were relatively weak, paleoclimate became the main factor causing 2–3 m fluctuations of the paleolake level. [Copyright &y& Elsevier]

A Holocene loess profile to the west of Xi''an China was studied multi-disciplinarily to investigate the relationships between soil erosion and monsoonal climatic change. The proxy data obtained from this aeolian loess and palaeosol sequence indicate large-scale variations of climate in the southern Loess Plateau since the last glaciation. A rainwash bed, indicative of a wetter climate, excessive runoff and erosion on the loess tablelands, was identified relating to the early Holocene before the onset of the “climatic optimum”. This is synchronous with the early Holocene physiographic erosional stage identified in the valleys in North China. It means that severe erosion took place when the region was undergoing climatic amelioration during the early Holocene. The evidence presented in this paper shows that the erosion occurred as a regional response to a monsoonal climatic shift in the southern Loess Plateau. During the last glaciation, prior to the erosion phase, the land surface on the tablelands had been largely stable except for the rapid accumulation of aeolian dust and the resultant increase in its elevation. Relatively slow dust accumulation and intensive bio-pedogenesis responding to the Holocene “climatic optimum” followed the erosion phase. The loess tablelands were most vulnerable to erosion during the large-scale monsoonal climatic shift from dry-cold glacial to humid-warm post-glacial conditions in the southern Loess Plateau. [Copyright &y& Elsevier]

• The on-line stresses of natural gas pipelines on collapsible loess were measured. • The key position for every typical cases to occur strength failure is analyzed. • An improving stresses distribution method was proposed by adding support pier. • The stresses of gas pipelines in the collapsible loess should be measured regularly. There are many collapsible loess foundations in the first-line project of West-East gas pipeline of China. The collapsible loess has a great influence of the structure integrity of pipeline, especially the stress distribution. In this paper, the stresses of natural gas transmission pipelines for compressor station on collapsible loess area were measured by indentation strain method. The key position for every typical cases to occur strength failure is analyzed. A failure prevention method was also proposed. The results show that the axial stress may exceed the tensile strength induced by download bend deformation of pipelines, and becomes a potential zone to occur strength failure. An improving stresses distribution method was proposed by using added support pier below the ball valve. The axial stresses can be reduced by proposed improving method which will enhance the strength of pipelines very well. The stresses of gas pipelines in the collapsible loess should be measured regularly to avoid strength failure. [ABSTRACT FROM AUTHOR]

Loess is a typical soil with the characteristic of water sensitivity, and in the study of water-induced geological disasters of loess distribution areas worldwide, special attention must be paid to the influence of this sensitivity. Hence, quantitative study of the water sensitivity of loess has been a basic scientific issue of wide concern. In this study, the water sensitivity characteristics of loess in the South Jingyang Tableland of China are investigated through oedometer tests and triaxial shear tests, and the variation in the structural strength, deformation modulus, and strength parameters of intact samples with different water contents is studied. It is found that the structural yield stress, initial deformation modulus and cohesion are sensitive to the water content, i.e., decreasing in the form of a power function or an exponential function with increasing initial water content. An analysis shows that the above parameters can be used to normalize the compression curves, stress-strain curves and critical state lines of loess. According to the quantitative formula of water sensitivity in the field of petroleum exploration, a new method to assess the water sensitivity of loess by analogy is proposed, which involves the structural strength, deformation modulus and shear strength parameters in the natural and humidified states. The analysis further indicates that the water sensitivity index proposed in this paper is a reasonable, sensitive and effective way to quantify the water sensitivity of loess. • The compression curves, stress-strain curves and critical state lines of loess can be normalized. • A new method for assessing the loess water sensitivity index is proposed. • A geomechanical model reflecting the micro-structural mechanical response process of water sensitive loess is presented. [ABSTRACT FROM AUTHOR]

Loess is a typical silt-sized Aeolian soil that is widely deposited and possesses a fragile soil structure susceptible to collapse upon wetting. The instability of shallow loess slopes is well documented, but deeper failures triggered by rainfall and irrigation can also occur. In the case of long-term seepage, clay particles and salts have been observed to leach out of the loess slopes. This paper presents a systematic laboratory study of the effects of water conditions on the mechanical behaviour of silty loess, with isotropic compression and bender element tests carried out on natural and reconstituted loess recovered at 10 m depth from a site in China. The results show that saturation causes reduction in both the compression yield stress and small strain stiffness of the soil, and that after being exposed to seepage, they decrease further. The possible mechanism of structure degradation is investigated by means of microscopic and chemical analyses, and it is found that seepage will cause the pore ions concentration to reduce with a loss of clay mineral bonding strength, resulting in the detachment of silt particles from aggregates. This work highlights the importance of monitoring the water outflow in the field at the loess slope edge, since it may causes large deformation in the long-term. • The effects of three different water conditions on the mechanical behaviour of a silty loess are studied. • Isotropic compression together with bender element tests is carried out on loess specimens. • The possible mechanism of structure degradation induced by seepage is investigated. [ABSTRACT FROM AUTHOR]

Loess caves, landslides, collapses, bank erosion and soil erosion, which are independently and interactively shaping the modern loess landscape, are widely distributed across the Chinese Loess Plateau. The study area is located in a small watershed in Huining County, Gansu Province, which is one of the areas with the strongest development of loess caves across the Loess Plateau. This area is an ideal site for studying geological hazards and geomorphic evolution on the Loess Plateau. Seventeen landslides and 176 loess caves with a density of 887 units/km2 were investigated with a UAV (unmanned aerial vehicle) and mapped by GIS (geographic information system). Using high-resolution UAV images and topographic data, we carried out an interpretation of loess caves, bank erosion and landslides; studied the spatial distribution and developmental patterns of loess caves, landform morphology and the relationship between loess caves and landslides based on GIS spatial analysis, mathematical statistics and field surveys; and analyzed the influence of loess microtopography on slope landforms. Finally, six typical evolutionary models of soil erosion-loess cave development-landslide occurrence-barrier dam formation are preliminarily proposed: the primary slope stage, early cave stage, accelerated cave stage, cave connecting stage, landslide creeping stage, and landslide-dam forming stage. This study is a useful exploration and an attempt to reveal the influence of loess cave development on slope stability and disaster chain effects. • This paper completed the high-resolution interpretation of loess geological hazards based on UAV. • Spatial distribution, developmental regularity and influences of loess caves were revealed. • Typical evolution model of the loess disaster chain was preliminarily proposed. [ABSTRACT FROM AUTHOR]

Earth fissures are major geological hazards that frequently occur in the Weihe Basin in northwestern China and can cause severe damage to infrastructure. This paper reports a case study of earth fissures resulting from loess collapse in the village of Xibai, in the Weihe Basin. A series of geological investigations, consisting of a site investigation, trench excavation, geological drilling, exploratory well drilling, and geotechnical testing, were conducted to determine and analyze the characteristics of the Xibai Village earth fissures, as well as the physical characteristics of the loess in the earth fissure development area. The earth fissures were parallel to the village sewage pit and had a total length of 800 m. With a maximum depth of 8.5 m, the Xibai Village earth fissures were nearly vertical. Comparing the results of self-weight collapsibility coefficient and three parameters (void ratio, dry density, and water content) of loess at different distances from the sewage pit, the collapsibility of Malan loess in this area and the effects of leakage from the sewage pit were determined. The results revealed that a tilted seepage line was generated, and the loess below this seepage line underwent varying degrees of self-weight collapse deformation. The nonuniform collapse settlement and rotation deformation of loess above the seepage line were thus generated, while tensile stress was created in the upper part of the loess. This rotation of loess, similar to the deformation of the cantilever beam, caused the formation of the earth fissures at the site with higher tensile stress. Based on the rotation mechanism, this study explained the development process of collapse earth fissures and predicted that the Xibai Village earth fissures would continue to develop outward in the future. • Leakage of sewage pit produces an inclined seepage line in loess. • Nonuniform collapse deformation of loess causes earth fissure. • Rotation of cantilever beam of loess is mechanics mechanism of collapse earth fissure. [ABSTRACT FROM AUTHOR]