摘要
为研究泥皮、粗糙度对桩-土接触面力学特性的影响规律,根据灌注桩成孔后的孔径-深度曲线,应用统计分析法获得了桩侧凸出尺寸和粗糙度的分布频率规律,以此构建了表面光滑和梯形凹槽混凝土板来模拟实际桩侧表面粗糙度。在此基础上,开展了不同泥皮厚度、粗糙度条件下的混凝土-砂土接触面大型直剪试验。其研究结果表明:无泥皮条件下粗糙接触面,其剪切应力-切向位移关系曲线呈软化型;泥皮厚度为5、10 mm条件下,呈硬化型。剪切模量G0.02随泥皮厚度增加而衰减。对光滑混凝土板,其接触面峰值剪切强度和峰值摩擦角随泥皮厚度的增加呈指数关系衰减;对粗糙混凝土板,峰值剪切强度和峰值摩擦角随泥皮厚度的增加近似呈线性衰减。初始泥皮越厚,试验后的泥皮土和泥皮越厚,接触面剪切强度越低。无泥皮条件下粗糙度对接触面峰值剪切强度的影响规律:存在一个临界粗糙度I_(cr)=10 mm,当混凝土板的粗糙度I<I_(cr)时,接触面峰值剪切强度和峰值摩擦角随粗糙度的增大而增大;当I≥I_(cr)时,二者随着接触面粗糙度的增大而减小,泥皮存在会影响改变这一规律。
To explore the influence of slurry thickness and roughness on the mechanical properties of pile-soil interface, the distribution of protrusion size and roughness on the side of pile is obtained by statistical analysis based on the relationship between diameter and depth of borehole. The surface roughness of the concrete pile is simulated by the surface smooth and trapezoidal groove concrete respectively. A series of large-scale direct shear tests of concrete-sand interface is conducted with different slurry thickness and roughness. The results show that for the rough interface without slurry, the shear stress-tangential displacement curve is softened. For the rough interface with slurry at thicknesses of 5 mm and 10 mm, the shear stress-tangential displacement curve is hardened. The shear modulus G0.02 at the horizontal shear strain value of 0.02 decreases as the slurry thickness increases. For smooth interface, the peak shear strength is decreased exponentially as slurry thickness increases. For rough interface, the peak shear strength and the peak friction angle are decreased in an approximately linear way as slurry thickness increases. The interface strength becomes damped as result of the increasing initial thickness of the slurry and the thickness of the mixed layer after the test. Furthermore, a critical roughness on the peak intensity of contact surface under no slurry condition is found. When the roughness of concrete slab is less than the critical roughness I_（cr）, the peak shear strength and the peak fiction angle of the interface will increase with the increase of roughness. When the interface roughness I is larger than I_（cr）, both of them will decline with the increase of roughness. However, the existence of mud changes the relationship between roughness and peak shear strength.
作者
陈琛
冷伍明
杨奇
金子豪
聂如松
邱鋆
CHEN Chen;LENG Wu-ming;YANG Qi;JIN Zi-hao;NIE Ru-song;QIU Jun(School of Civil Engineering, Central South University, Changsha, Hunan 410075, China;National Engineering Laboratory for High Speed Railway Construction, Central South University, Changsha, Hunan 410075, China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2018年第7期2461-2472,共12页
Rock and Soil Mechanics
基金
国家自然科学基金资助项目(No.51478478
No.51678572
No.51208518)
中南大学研究生科研创新项目(No.2017zzts159
No.2017zzts741)~~
关键词
桩-泥皮-土接触面
大型直剪试验
临界粗糙度
峰值剪切强度
峰值摩擦角
pile-slurry-soil interface
large-scale direct shear tests
critical roughness
peak shear strength
peak friction angle
