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Abstract The seismic deterioration effects of anchor cables and slope structural planes are often neglected in the dynamic stability analysis of anchored rocky slopes to the extent that the stability of slopes is overestimated. In this paper, a dynamic calculation method for anchored rocky slopes considering the seismic deterioration effect is established, and a stability evaluation method for anchored rocky slopes based on the Gaussian mixture model is proposed. The seismic deterioration effect on the stability of anchored rocky slopes is quantitatively analyzed with an engineering example, and the relationship between seismic intensity and the failure probability of slopes is clarified. The results show that compared with the calculation method without considering the seismic deterioration effect, the minimum safety factor and post-earthquake safety factor obtained by the proposed method in this paper are smaller. The number of seismic deteriorations of the slope is used as the number of components of the Gaussian mixture model to construct the failure probability model of the slope, which can accurately predict the failure probability of anchored rocky slopes. The research results significantly improve the accuracy of the stability calculation of anchored rocky slopes, which can be used to guide the seismic design and safety assessment of anchored rocky slopes.

Based on a foundation pit project in Fuzhou, China, the influence of foundation pit excavation on the supporting structure and surrounding environment in a soft-soil area is studied. This study was based on actual monitoring data and investigated the variations in the supporting structure, surrounding constructions, and groundwater levels during excavation. The analysis of the monitoring data demonstrates the presence of pronounced ‘spatial effects’ and ‘temporal effects’ on the deformation of the support structure and surrounding structures. The deformation of the support structure and surrounding structures exhibits distinct spatial distribution characteristics at different locations along the excavation pit wall. Typically, more significant deformations are observed in the middle section of the pit wall, while deformations decrease as the distance from the pit corner decreases. The support structure’s and surrounding structures’ deformation characteristics vary during different construction stages. During the excavation phase, the rate of deformation increase in the support structure and surrounding structures is notably higher. In contrast, during the construction of the underground basement floor and the backfilling phase of the excavation pit, the rate of deformation increase in the support structure and surrounding structures is relatively lower. Throughout the entire construction period of the excavation pit, the groundwater level in the vicinity of the pit exhibits a fluctuating trend. Apart from the influence of rainfall, the overall variation in groundwater level is minimal, indicating the effective water-sealing performance of the combined Soil-Mixing Wall (SMW) support structure within the circular enclosure.

In addition to selecting an effective support structure to control deformation, precipitation and water stopping should also be considered when designing a support scheme for water-bearing foundation pits in soft soil areas. This paper presents a detailed description of the foundation pit support scheme, the precipitation and water-stopping scheme, and the monitoring scheme of the foundation pit project of Taijiang Square in Fuzhou. During the construction of the foundation pit, the monitoring data of 12 items such as the deep horizontal displacement of the enclosure pile, the horizontal displacement at the top of the foundation pit, the settlement at the top of the foundation pit, the axial force of the internal bracing, and the axial force of the enclosure pile were obtained through 12 months of monitoring. The analysis of the monitoring data for each item led to the following two main findings. The first finding is that, during the construction of the pit, the monitoring values of the 12 monitoring items did not exceed the alarm values, which proves that the support scheme of the cast-in-place pile enclosure structure and internal bracing can meet the design requirements of deep foundation pits in soft soil areas. The second finding is that tube-well dewatering is an effective way to lower the groundwater level in water-containing deep foundation pits in soft soil areas, and double-wheel deep-mixing water-stopping curtain walls can effectively control the infiltration of groundwater outside the water-containing deep foundation pits in soft soil areas. This foundation pit project is representative, and it provides a good reference case for the design of water-bearing deep foundation pit projects in soft soil areas.

The pile-soil stress ratio (PSSR) is the key to the design and construction of geosynthetic-reinforced pile-supported (GRPS) embankments. However, the computation models for the PSSR which takes account of the effect of consolidation settlement of soil among piles (SAP) is not complete. This paper splits the piles and the SAP into multiple small elements for iterative calculation, according to the principle of the collaborative actions between pile, soil, embankment and reinforcement. The calculation method for pile-soil interaction was improved by Davis’ 1D nonlinear consolidation theory, and the hyperbolic load transfer model of pile-soil interface proposed by Wong and Teh. Then, a novel computation model for the PSSR of GRPS embankments was established, under the joint impact of soil arching effect, tension membrane effect and improved pile-soil interaction. Finally, this proposed computation model was proved reasonable by the comparison with tests and other methods, and the effects of key parameters were investigated. The results show that the settlement difference between piles and SAP increased with the degree of consolidation of the SAP and the elapse of time; the PSSR below the reinforcement net (RN) is slightly higher than that above the RN; the PSSRs above and below the RN are both positively correlated with the degree of consolidation and initial bulk compressibility of the SAP.

Low-grade concrete-cored sand-gravel (CCSG) pile composite foundation is a new kind of composite foundation for thick and soft clay ground treatment. An analytical solution was derived for calculating the consolidation process of this composite foundation by considering coefficients of horizontal permeability in smear zone, the radial flow within the sand-gravel shell, and the impervious property of concrete-cored pile. The results show that Terzaghi’s one-dimensional consolidation solution and the consolidation analytical solution of ordinary composite foundation were special cases of this solution. Curves of the average consolidation degree of the composite foundation under various nondimensional parameters were observed using the program based on the theoretical formula. Meanwhile, a series of in situ measurements including the settlement of pile and soil, the pore water pressure, and the total stress under embankment load were obtained on the CCSG pile composite foundation on a section of Zhenjiang-Liyang highway. The analyzed results show that the new style composite foundation patent technology has many advantages such as small differential postconstruction settlement (differential is not good, small is), reliable quality, high bearing capacity, and stability. And the consolidation of composite foundation is largely affected by the nondimensional parameters. The analytical solution is finally verified with the actual measurement data.