Applied Mechanics and Materials Vols. 744-746

Abstract: the construction method of the ordinary cemented soil stiffness core composite pile is that the pile peripheral cemented soil and the core pile are constructed at different time, which might lead to the situations as the pile body is broken due to the forced inserting of the core pile into the cemented soil mixed pile after the initial setting time, the neighboring finished pile is damaged due to the compacting effect caused by the reaming construction of the core pile and the failure of effectively transferring the load due to the loose joining of stiffness core pile and the cemented soil whose construction is completed after the initial setting time. This paper aims to overcome the defects of the conventional construction method by introducing a new construction technology, and the construction technology is verified to be reliable through the application in the actual engineering projects and has the advantages that the peripheral soil body is significantly strengthened, the composite pile foundation can effectively overcome the harm as uneven settlement of buildings, so as to ensure the normal usage of the buildings, and the construction technology has excellent economic benefits and is significant for the later construction technology for treating the soft soil foundation.

Abstract: Based on the investigation of soil slope in Zhejiang province, the main influence factors of soil slope stability were analyzed and the risk assessment indexes of soil slop were selected. Then the risk assessment model of soil slope was established by the method of analytic hierarchy process according to the importance of each index. The security risk assessment system of soil slope was obtained finally. The research result has important reference for the soil slope management.

Abstract: Large size loading plate test for sand compaction pile composite foundations with the replacement ratio being up to 60% was carried out to study the deformation and bearing capacity of the sand compaction pile composite foundation. The test was carried out for 53 days with anchor pile, square loading with the side length of 5.4m, 15m-deep water and twice circulation loading mode. The compression deformation, pile-soil stress ratio and deformation modulus of the sand compaction pile composite foundation was analyzed through load test. Test results indicated that, the ultimate bearing capacity of the sand compaction pile composite foundation in this test was larger than 340kPa; sand compaction pile had a drainage consolidation effect on the soft soil between piles; under the load-keeping condition, sand compaction pile composite foundation would also has settlement; pile-soil stress ratio was 6.3 and deformation modulus was about 8kPa. The success of the test may provide experience and reference for load test of underwater sand compaction pile composite foundation carried out at open sea.

Abstract: Deep Pit is the main content of modern urban geotechnical engineering. In this paper, based on a deep foundation pit engineering as an example, based on the nonlinear finite element theory, conduct a numerical simulation research for foundation pit excavation process. Obtained the distribution law of pit deformation, stress distribution and the supporting structure of the internal forces, under the various processes. These provide a theoretical basis for safety evaluation of foundation pit engineering.

Abstract: Peridynamic simulations have been carried out to perform the slope stability analysis. A slope is first modelled with discretized particles in 2D. Then the non-ordinary state-based Peridynamic model is utilized. In order to obtain a more realistic behavior of the soil, Drucker-Prager constitutive model is used to describe the mechanic properties of soil. Results show great agreements with the FEM results, while provides the dynamic slide progress in the post-failure process.

Abstract: Traditional vacuum preloading method has two drainage parts: 1) horizontal drainage part-sand cushion; 2) vertical drainage part-(Prefabricated vertical drain (PVD) and so on). During vacuum preloading process, the drainage effect of horizontal sand cushion is strong near stabilized soil surface and decreases rapidly at deeper position, while drainage range of vertical drain includes whole stabilized soil depth and its drainage ability is higher. So, it is important to improve the drainage design of vacuum preloading system to transmit vacuum head to vertical drain more efficiently. This paper presents a new vacuum preloading method-direct drainage vacuum preloading method (DDVP method). Compared with traditional vacuum preloading method, this system cancels horizontal drainage part-sand cushion and uses sealed pipe to directly connect with PVDs. Vacuum head can be transmitted into PVD without attenuation. Field test is applied to study the effect of slurry improvement of this method.

Abstract: When calculating the dam slope failure process, traditional strength reduction method doesn't consider the difference of decay rate between cohesion and internal friction angle and discount the strength parameters for all elements. This paper uses two different reduction factors for material strength parameters, slope cohesion and internal friction angle. Based on the yield approach index criterion, we change the reduction region in time and put forward a double safety factor of dynamic local strength reduction method for engineering analysis of dam slope stability.

Abstract: In view of the holes appearing in different area of geo-membrane when the geo-membrane technology is applied to the unsaturated expansive soil slope, the VADOSE/W is used to analyze the wetting-drying cycles caused by rainfall and evaporation on slopes covered by geo-membrane. The influence on the pore-water pressure and volume water content were discussed just caused by the holes. The results show that the hole is nearer to the toe of slope, its impact on the whole seepage field is greater. In addition, the hole appears on the top of slope that the wetting-drying cycle effect is remarkable. It is ensured that the integrity of the geo-membrane which in the lower slope and take some drainage measures in the construction process.

Abstract: In recent years, with the increasing of excavation activity, caused the landslide more and more increasing, the landslide occurred gradually aroused public concern. For typical loess landslides caused by excavation, respectively from the distribution features of the landslide, landslide characteristics after wall, slope high on the impact of landslides and landslides trailing edge fracture characteristics were analyzed. Statistics show that the engineering loess landslides in the distribution respectively are selectivity of landform, strata of selectivity and zonal distribution. The excavation methods are rapid excavation and “eating” excavation. Landslide back wall angle is between 60-80°. The height of the scarp is between 3-20m, controlled by the thickness of the Malan loess. The slope high is more than 60m, with the increase of height. The risk of slide is higher. Trailing edge crack development is “wild goose feather” type and “bilateral ears” type. It provides conditions for trailing edge of evolution.

Abstract: Building on the foundation with steel slag as a typical example of the destruction of the thermo-elastic theory to study slag landfill foundation, combining academic knowledge mechanics, heat transfer, etc., the theoretical foundation of slag analysis and numerical simulation of thermal stress, a comprehensive discussion the failure mechanism of the upper part of the foundation of the slag building. On-site measured temperature were fitted by thermal stress analysis of steel slag field, get the corresponding stress-strain cloud. The results show close to the simulation results and the actual situation: simulating thermal stress results slag surface be uplifted 3.77cm, uplifting 5cm of building fundamentals actual.