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Geobelt, made of polymeric materials, is one of the reinforcement materials. In the present study, a large site loading test program was performed on a square footing supported by the geobelt-reinforced crushed stone layer on the soft soil. The reinforced soil layer is thin, in which the ratio of the reinforced soil layer depth and the footing width is only 0.2. The various parameters studied in this testing program include the number of geobelt layers, the depth of first geobelt layer beneath the footing, the vertical spacing between two geobelt layers, and the linear density of reinforcement. The results show that the performance of the geobelt-reinforced crushed stone cushion was obviously improved compared with unreinforced crushed stone cushion. For one layer of geobelt reinforcement, the effect of the geobelt reinforcement is mainly controlled by the depth of first geobelt layer beneath the footing and linear density of reinforcement. With a shallow depth of the geobelt layer of reinforcement, it works efficiently at a small settlement of the footing. The beneficial effect of a double layer of geobelt is greater than that of a single layer, especially when the settlements are concerned.

GEO-groove simulation experiment is applied to imitate the Taiyuan soil subsidence in pipeline base and side by soil loss, which eventually leads the pipeline to be deformed and destroyed. The pre-damage standard is set up though analyzing test statistics and drawing it’s sedimentation and damage curve. The damage standard of sewage line is achieved through setting up a very pilot model to the test and analyzing it’s bearing force characteristics, and according to the gotten sedimentation curve of the test, damage characteristics and mechanism of sewage line is analyzed , thus will give the designing and application of pipeline of testing and theory basement, so as to take measures to protect pipeline in practical situations, establish early warning system to pipeline, and guarantee it’s regular service.

Currently it is still a lack of reliable evidences on the evaluation of the bearing capacity of foundation in highway construction of Shanxi Province. Mainly reason is that the method widely used to determine in bearing capacity of loess foundation in building structures is not completely suitable to length and wide range of highway subgrade project. Because Shanxi loess region terrain is very complex, the capacity of Q3 loess-like silt in Yuncheng of Shanxi is collected and analyzed, based on statistics of a large number of bearing capacity from site loading tect. A linear regression relationship is established between loess foundation bearing capacities and water content, liquid limit, void ratio. Another linear regression relationship is established between saturation and liquid limit void ratio . Meanwhile, it compares these two sets of linear regression relationship with the measured bearing capacity and the carrying capacity by specification. Applied result show that the relative errors of the bearing capacities computed by the formulas are less than 10%, compared with other standard methods to determine the loess bearing capacity. It is significantly improvement for meeting the requirements of the highway construction.

Through the model test in soil slot,the process of deformation and destruction of soft pipeline caused by subsoil settlement is simulated and observed in lab. Based on the experimental data, the curve as the internal force of pipeline is first drawn out and discussed, in turn the characteristic of stress distribution and destruction rule of pipeline are analyzed and summarized, which may be referred for designer to take appropriate measures. The experimental results show that the internal force and deflection of the pipeline increase with the depth and width of the hole below the pipeline. When the hole depth (h)/ pipeline diameter (D) =2.5, internal force and deflection changes only associate with the width of the hole (b). And when b/D =6, the pipeline can not work normally and even be destroyed. The experimental conclusion can provide the basis for the security of underground pipeline.

The subject of Foundation Excavation near the buried pipeline line. Compared with each other using a scale model of the buried pipeline foundation excavation factor of the vertical displacement, and connected with the buried pipeline displacement of both ends of the fixed elastic beam theory; analysis of the factors affecting the displacement of buried pipelines, the good agreement of the theoretical results with the scale model test value.

A series of compression tests were conducted on the samples taken from compacted soil site in Lulling, in order to investigate the compressibility of compacted loess in different water content and different compaction energy. Through statistics analysis of the testing data, the stress-strain curve of compacted loess could be expressed with Hyperbolic form. And the relation between initial tangent modulus and water content change coefficient was founded by introducing the water content change coefficient. The result shows that at the same compaction energy, the initial tangent modulus decreases and the ultimate strain increases as water content increases; while at the same water content change coefficient, the initial tangent modulus increases and the ultimate strain decreases as compaction effort increases.

This paper studies the microstructure of 16 group samples from three different sites of North-west region in P. R. China. Pictures of microstructure were processed with imaging processing program to acquire the geometer parameter and fractal dimension of pores. The range of pores’ fractal dimension is between 1.816~1.936. The pore distribution function of unsaturated soil is established based on fractal geometry theory. The pore water distribution of loess under natural moisture is analyzed. The relationships of collapsibility coefficient with fractal dimension and porosity of unsaturated pores are analyzed with the method of regression analysis. A larger fractal dimension represents a more complex pore-structure. The collapsibility coefficient of loess increases with the increase of fractal dimension and porosity of unsaturated pores.

The degree of compaction is usually used as the compaction quality and control indicator of backfill in practical project. However, as the degree of compaction is affected by various internal and external factors, its accuracy is difficult to guarantee. In this paper, compacted loess samples were prepared under different compaction energies by normal compaction method. The curves of compression coefficient and dry density, the compression coefficient and porosity of compaction loess samples under different compaction energy are analyzed while the water content is constant. The air porosities of compaction loess samples under different compaction energy and water content are calculated and summed up. The air porosity of compaction loess samples under different compaction energy is more stable than the degree of compaction when the water content is exactly equal to the optimum water content. The rationality of using air porosity as the loess compaction quality control indicator is discussed. It is proposed using air porosity as additional indicator of compaction quality control on the condition of the loess compacted dry density meeting the requirements. The air porosity less than 6.5% is suggested as the additional quality control indictor for region backfill compaction.

Contamination can change the physical properties of soil, reduce the strength of cemented soil foundation, and then induce the instability or disruption of buildings. This study explored the relationships among the age, electrical resistivity, unconfined compression strength, contamination of municipal sewage concentration. Firstly, we mixed the silty clay with municipal sewage of five different concentrations to form the contaminated soil. Then, mixed the contaminated soil with ordinary portland cement to form the cemented soil blocks. Finally, measured the unconfined compression strength and electrical resistivity of these blocks. The results show that the unconfined compression strength and electrical resistivity increase linearly with the increase of the logarithm of age, and decrease exponentially with the increase of municipal sewage concentration. The unconfined compression strength of cemented soil has a linear relationship with its resistivity. The municipal sewage concentration and age can be use to predict the unconfined compression strength of cemented soil.The predicted values correlate well with the experimental values.

With the Drucker-Prager yield criterion, the ANSYS software is used to analyze the long-short-pile composite foundation by using three-dimensional nonlinear finite element method. The influences of load on axial stress and maximal axial stress of head of pile with cushion or not have been investigated by simulating composite foundation through nine long piles and sixteen short piles. The result indicates the cushion can reduce the stress concentration in head of pile effectively with increase of load. This conclusion has a certain value for engineering.

As a simplify and effective method , electrical resistivity has been used in geotechnical engineering. In lab the experiment simulated that cemented soil had been polluted by industrial sulphuric acid after mixing. On different age time, the variation trend among electrical resistivity of cemented soil and solution, formation factor and solution concentration were studied. The results indicated that both of electrical resistivity and formation factor have close correlations with sulphuric acid solution concentrations and pollution level of cemented soil. This shows that the electrical resistivity method are very sensitive for groundwater and cemented soil after pollution in the engineering site.

Cemented soil resistivity is one of its inherent properties which can be used to detect its unconfined compressive strength and polluted state. But the cemented soil resistivity is macroscopic showing of its microstructure conductivity. Its resistivity closely relates with resistivity of various material components, such as soil porosity, cement mixing ratio,etc. So further researching the electrical model of cemented soil is great significance. This paper introduces the existing cemented soil electrical model(Komine model). Then based on the microstructural observation of the SEM images of cemented soil, the problems of Komine model are pointed out. Furthermore a more reasonable microstructure is proposed. The new electrical model of cemented soil is set up on three hypotheses. This new model is composed of parallel structure and series structure. Some soil particles surrounded by the hydration products such as CSH or CASH connect with pore water parallel to form the series structure. The hydration products that continue to harden to form the cemented soil skeleton connect with soil particles and pore water to form the parallel structure. The new electrical model of cemented soil can explain better electrical conductive mechanism of cemented soil materials.

Since geogrids with triangular apertures have a more symmetrical and therefore more stable structure than biaxial geogrids, they are expected to provide more uniform resistance in all directions. Laboratory model tests were performed in this study to evaluate the bearing capacities of triangular aperture geogrid-reinforced bases under static loading. Unreinforced bases and biaxial geogrid-reinforced bases were also tested for comparison purposes. In this study, the influence of aperture shape, location, and number of geogrids on the bearing capacity were investigated. The test results showed that all the reinforced sections performed better, when the geogrid was placed within the depth of 2/3 of the plate diameter, than the unreinforced section. Triangular aperture geogrids had higher capacity to weight ratios than biaxial geogrids.