| With the process of urbanization in China,the scale of town is becoming larger and larger,and the land resources of the town are becoming more and more tense.It is often needed to build the building in the position on the top of the slope.For the rock slope with fracture surface,it is stipulated that the pile should not be supported on the potential sliding body of the slope,and the pile end should enter the stable rock layer below the potential fracture surface,and take effective isolation measures to reduce the vertical load of pile foundation to slip body.The pile foundation passing through the potential rupture surface not only bears the vertical load transmitted by the upper building,but also bears the sliding force of some sliding bodies.The research on the distribution of the lateral friction resistance,shear and bending moment of the pile foundation through the rupture surface can increase the accuracy of the design of the isolated pile in the future,and the study on the pile length of the rock slope in the fracture surface,and put forward the design condition that the pile end does not enter the fracture surface,which is of the unusual significance.The main contents and conclusions of this paper are as follows:(1)Through the indoor model test,the distribution of pile side friction resistance under the condition of three kinds of isolation measures(asphalt felt,polyurethane coating,polyurethane coating +5% graphite powder)is studied and compared with the side friction of the pile under the non-isolation measures,and the isolation effect of the three kinds of isolation measures is studied.It is found that:(1)There are two peaks in the distribution curve of the pile side friction along the depth of the rock,and the peak friction resistance of the upper side of the pile is obviously larger than the peak of the lower pile side when the pile foundation has no isolation section.(2)Three isolation methods can be applied to different degrees of isolation,but they can not be completely eliminated.When using polyurethane coating +5% graphite powder to isolate,the economy is high and the isolation effect is the best.(2)Relying on concrete engineering examples,the shear and bending moment of the pile foundation through the fracture surface under the strength of different fracture surfaces,different rock strength and different support conditions are analyzed by FLAC3 D.It is found that:(1)The shear force and bending moment of the pile foundation are very small when the anti-sliding force of the rupture surface is greater than that of the sliding body or the effective support of the slope.(2)When the pile top is connected with a rigid beam,the bending moment and sheer force of the pile foundation can be even more uniform,but the bending moment and shear strength of the pile foundation are limited.(3)The effects of different pile lengths on the overall stability of the slope under the conditions of cohesive force,internal friction angle and slope support are analyzed by FLAC3 D.It is found that:(1)The safety factor of the building rock slope has a critical value with the cohesion of the fracture surface and the change of the internal friction angle.When the cohesion and internal friction angle is less than the critical value,the safety factor of the slope is linearly varying with the cohesion and the internal friction angle;and the safety of the building rock slope is safe when the cohesion and internal friction angle are greater than the critical value.(2)The coefficient no longer increases,when there is an effective anchorage section when supporting the slope,it should be selected as the appropriate anchorage length so as to avoid unnecessary waste.(3)If the shear strength of the rupture surface is greater than that of the sliding body or the slope is effective,the pile foundation can be placed above the fracture surface. |
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