【作者】 闫金凯；

【导师】 殷跃平；

【作者基本信息】 长安大学 ， 地质工程， 2010， 博士

【摘要】 微型桩由于具有非开挖施工、对土层适用性强、桩位布置灵活、施工速度快、对滑体扰动小等优点,近年来在滑坡防治中得到了越来越多的应用。但由于其应用时间短,人们对其在滑坡防治中的受力变形特性没有足够的了解,致使其设计计算理论远远落后于工程应用。本文依托国土资源大调查项目“滑坡灾害微型桩防治技术大型物理模型试验”,通过室内物理模型试验、大型物理模型试验及有限元数值模拟相结合的方法,对不同配筋形式的微型桩单桩、排桩、群桩在滑坡防治中的受力变形特性进行了研究。试验证实微型桩应用于滑坡防治是可行的。取得的主要认识如下：(1)微型桩所受的滑坡推力基本呈三角形分布,滑面附近土压力最大,随滑坡的滑动,合力作用点不断下移,临滑时合力作用点距滑面的距离略小于1/3受荷段桩长；桩后滑体抗力主要分布于受荷段中部,滑面及桩顶附近土压力较小,基本呈抛物线形分布；滑床抗力沿深度方向分布不均匀,滑面附近的桩后滑床抗力较大。(2)微型桩群桩中的各排桩同时受力变形,滑坡推力沿滑坡滑动方向按15%的幅度递减,试验中最后排桩所受的滑坡推力仅为第一排桩的1/3。(3)不同抗弯刚度的微型桩的破坏形式不同。采用桩心配筋形式的微型桩抗弯刚度较小,受力后容易于滑面附近发生弯折破坏,使微型桩的抗剪能力得不到发挥；桩周配筋形式的微型桩抗弯刚度相对较高,于滑面附近发生弯曲与剪切相结合的破坏。群桩各排桩破坏形式基本相同。(4)微型桩受荷段承受负弯矩(背滑侧受拉),单桩与群桩的弯矩分布范围不同,单桩受荷段弯矩集中分布于滑面上10倍桩径的范围,群桩受荷段弯矩分布于整个受荷段,其中滑面上15倍桩径范围内弯矩较大。群桩与单桩受荷段最大负弯矩均位于滑面上7倍桩径处。微型桩嵌固段主要承受正弯矩(迎滑侧受拉),且分布于滑面下10倍桩径的范围内,最大正弯矩位于滑面下5倍桩径处。(5)群桩各排桩的剪力分布形式基本相同,位于滑面下7倍桩径～滑面上7倍桩径范围内的剪力方向与滑动方向相同,最大正剪力位于滑面处；滑面上7～20倍桩径与滑面下7～23倍桩径范围内剪力方向与滑坡滑动方向相反,受荷段最大负剪力约位于滑面上13倍桩径处,嵌固段最大负剪力约位于滑面下12倍桩径处。(6)微型桩破坏后依然具有一定的抗滑能力,但破坏前后的抗滑机理不同。破坏前主要是微型桩的抗弯及抗剪能力起抗滑作用,破坏后主要是钢筋的抗拉能力起抗滑作用。更多还原

【Abstract】 Micropiles have been used in landslide reinforcement more and more recently because of the merit that little machinery, adaptability to stratum, rapid constructing speed, low influence to the landslide. But due to its short application time, people have no enough understand to the characteristic of micropiles in landslide reinforcement. Relying on the China Geological Survey item“Large scale model text on micropiles in landslide reinforcement”, the paper studies the characteristic of single micropile, micropiles in low, micropile groups with different reinforcement arrangement in landslide reinforcement. The main results of research as follows:(1) The landslide push force effecting on micropiles is distributed as triangle. The focus of resultant force approaches to the sliding face as the the stability coefficient of the landslide debases. The focus of resultant force lies in 1/3 pile length up the sliding face when the landslide slides. The landslide resistance behind the micropiles is distributed as parabola. The landslide bedding resistance is different along the depth and that near the sliding face is bigger.(2) Each micropile in micropile groups effects force and deforms at the same time. The landslide push force effecting on each micropile reduces by 15 percent along the sliding direction. The landslide push force effecting on the last micropile is only one of third of that effecting on the first micropile.(3) The damage form of micropiles with different reinforcement is different. The damage form of micropiles with center reinforcement arrangement is bending failure near the sliding face. The damage form of micropiles with surrounding reinforcement arrangement is cutting and bending failure in the sliding face. The damage form of ecch micropile in cluster is same.(4) The pile body above the sliding face effects negative bending moment but the scale is different in single micropile and micropiles in cluster. The bending moment in single micropile lies in ten pile diameters above the sliding face while that in micropile groups lies in the whole pile body above the sliding face. The biggest negative bending moment lies on seven pile diameters above the sliding face. The pile body that in the scale of ten pile diameters down the sliding face effects positive bending moment and the biggest of that lies on five pile diameters down the sliding face.(5) The shearing force of each micropile in pile cluster is same on the whole. The shearing force in the area from seven pile diameters down the sliding face to seven pile diameters above the sliding face has the same direction with the sliding. The biggest shearing force lies on the sliding face. The shearing force in the area from seven pile diameters to twenty-three pile diameters down the sliding face and from seven pile diameters to twenty pile diameters above the sliding face has the negative direction with the sliding. The biggest negative shearing force lies on thirteen pile diameters above the sliding face and twelve pile diameters down the sliding face.(6) Micropiles still have skid-resisting capacity when failure. But the skid-resisting mechanism is different. Before failure the shear-bearing capacity and bending resistance of micropiles effects while failure the pulling resistance of the steel effect.更多还原