Search

The bedding rock mass is a common geological configuration in earthquake engineering, and the wave method is often used in seismic response analysis, but the accuracy of the analysis is restricted because of the viscoelastic boundary parameters can only be take approximate values. In order to select the most reasonable approximation of boundary parameters in the analysis, in this paper, based on the transversely isotropic constitutive relation of the bedding rock mass, the existing methods of spring coefficients and damping coefficients are compared and analyzed, and the suggestion for the approximate values of the viscoelastic boundary of the bedding rock mass is given.

A method for the determination of arsenic speciation in municipal solid waste incineration fly ash was developed by high performance liquid chromatography (HPLC) coupled with hydride generation atomic fluorescence spectroscopy (HG-AFS). Before determination, various forms of arsenic were extracted with phosphoric acid through microwave digestion. The effect of phosphoric acid in the extracted solution on the speciation analysis of inorganic arsenic (As(III)/As(V)) was studied in detail. The results showed that when using diammonium phosphate as the mobile phase, the determination of As(V) was adversely affected. The increasing flow rate of mobile phase hardly reduced the adverse influence caused by phosphoric acid. The adverse influence was effectively suppressed when a mixed solution of disodium hydrogen phosphate/potassium dihydrogen phosphate (pH = 6.864) was used as the mobile phase. By using the improved method, As(III) and As(V) could be separated in 5 min, and the detection limits of As(III) and As(V) were 0.063 μg L−1and 0.110 μg L−1, respectively. The recovery rate of As(III) and As(V) in spiked standard sample was satisfactory (86.9%–102.6%). The determination of arsenic species in fly ashes sampled from four different municipal solid waste incineration plants were successfully accomplished by using the method. The results showed that the arsenic was predominantly in the form of As(V).

3D finite element analysis is utilized to calculate stress and internal forces in three different lengths of reinforced concrete segment for oil and gas shield tunnel subject to water and earth pressure by means of load-structure model. The rational length of concrete segment is determined to be 1.2m long after comparing the calculated stress and internal force in concrete segment with length of 1.0m, 1.2m and 1.5m respectively. Meanwhile, the safety factor is also compared in order to determine the rational length of concrete segment. The analysis shows that segment length for oil and gas shield tunnel with small cross-section should be less than 1.2m so as to facilitate its transportation and erection on construction site.

This paper summarizes the basic design of reinforced concrete segment for cross river shield tunnel in gas pipeline project, meanwhile discusses its assembly style and water-proof technique. One loop of shield tunnel is divided into six pieces of precast reinforced concrete segment which is assembled with screw bolt and stud. In addition, Waterproof technique such as self-waterproof of segment, elastic rubber gasket and water swelling rubber strip is used to ensure waterproof performance of shield tunnel. The presentation of this paper may provide guidance for the design of reinforced concrete segment for cross river shield tunnel.

In terms of oil and natural gas pipe to be installed in working shaft, and in light of basic dimension of slurry shield machine and its supporting system, required parameters of working shaft, such as its diameter, lining structure, building envelope have been presented in this paper. Meanwhile, the thickness of building envelope and permanent concrete lining for working shaft is also proposed through the analysis of its elastic stability and anti-buoyancy under influence of earth and ground water pressure.

This paper summarizes the design of open-cut subway station in Chengdu Metro line one. The station is built by cut and cover method and divided into three special parts with four different cross-sections used for main line and transfer track. Such retaining techniques as bored piles, steel pipe struts, soil nails, rock-bolts, steel-meshes, shotcrete and anchored steel cables are comprehensively used to maintain the stability of foundation pit. The anti-buoyancy coefficient of the open cut station is also derived and attains the requirement of safety and stability for the foundation pit after the utilization of these enclosure measures. The application of the design and construction technique for the subway station may provide guidance for the building of analogous subway station under similar geological and hydrogeological conditions in Chengdu.