| 4.14 Yushu Earthquake caused landslide of accumulated slope in Yushu airport section of National Highway G214, thus forming three landslide groups, i.e.0#,1# and 2#. The stabilizing structures in existence along the highway was damaged irregular. In order to guarantee the highway unobstructed when earthquake happens again. So it is essential to design some more new stabilizing structures to reinforce the slopes. But the place where landslide occurred was loose in the accumulative-layer. It was difficult to determine the figure, distribution and dynamic changing process about the force on the structures triggered by the seismic land sliding affection. This problem is also the one which need to be solved primarily in the design of stabilizing structures in Yushu airport road. Many studies have been done on the interaction between seismic landslide body and stabilizing structure in terms of the pseudo-static analysis both at home and abroad, while little in terms of the part on dynamic response properties. The earthquake-induced landslide and supporting structure is not investigated and specified to the extent of concrete forms; therefore, they are ambiguous. In current design specifications of supporting structure, force imposed on supporting structure is taken into consideration, while displacement of the structure and strain is not. Thus the design specifications are not complete in terms of content.In light of this, the paper combines the technology project of traffic construction of Qinghai Province-Research on treatment of landslide (highway) and preventional and control technology of slope disaster caused by Qinghai Yushu earthquake "(NO:2010-03).No.4 landslide in landslide group 0# in Yushu airport section of National Highway 214 was used as the site to conduct the study. And 4 groups of common seismic landslide with stabilizing structure models in the similarity ratio of 1:75 were designed to carry out large-scale shaking table model tests to research the dynamic response properties on the stabilizing structures in seismic landslides occurred in the accumulative-layer and supporting effect, which included dynamic response test of multi-row anti-slide pile, of pile top constrained anti-slide pile, of multi-anchor-point prestressed anchor sheet pile wall and of cluster pile anchor structure (compound supporting structure). Above all, all the research will be for the purpose to apply the theoretic foundation on the actual design of the seismic landslides. In this thesis, main conclusions include:1. The distribution form (behind) of earthquake dynamic earth pressure on multi-row anti-slide pile and pile top constrained anti-slide pile and multi-anchor prestressed anchor sheet pile wall anti-slide pile is similar to residual soil pressure, which both demonstrate R-type distribution. The site with the largest force in loading part is about one third above the sliding plate, and the site in anchoring part is near the bottom of the pile. The distribution form (front) is similar. The site with the largest force is the sliding plate. When the plasticity of soil body is damaged, the site with the largest force in loading part is about two third above the sliding plate, and the site in anchoring part remains unchanged in general.2.The anchor equipped changes the stress state of the anti-slide pile, thus producing an opposite effect on soil body. A more uniform growth in earth pressure in cantilever part of pile is lead to, and the earth pressure value is closer to certain value. The pressure of prestressed anchor cable under the seismic condition is determined by ground motion input. Strain amplitude first increase, then decrease, and finally increase with the increase of PGA. At the same time, prestress loss occurred, and therefore, the safety reserve of the cable should be paid attention to. Earthquake of 9 degrees and high intensity caused small displacement of the pile top. Anchor exerts a significant effect in reducing displacement.3. The input earthquake acceleration is a main factor influencing model seismic response characteristics. Earth pressure, residual earth pressure, displacement, strain, and acceleration amplification factor not only are affected by input earthquake acceleration, but also increase with the increase of PGA. Model seismic response characteristics is more significant under XZ bi-directional seismic loading than under X unit-directional seismic loading, which demonstrating that vertical seismic loading enhance the overall seismic effect.4. The test shows that against accumulated layer landslide, different kinds of supporting structure demonstrated different effects after earthquake:compound supporting structure (prestressed anchor cable frame structure with+micro pile)> multi prestressed anchor cable pile plank anti-slide structure> single anchor prestressed anchor pile plate anti-slide structure> pile top constrained anti-slide pile supporting structure> common anti-slide pile supporting structure. Multi-row supporting structure has a better anti-slide effect than single row anti-slide supporting structure under seismic loading. |
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