针对传统钻孔剪切仪剪切速率难以控制、测试误差大、试验参数取值依靠经验等缺点，研制了新型电控式钻孔剪切仪，并阐述了新仪器的结构、测试原理及方法。为测试新仪器的稳定性，将新仪器应用于滑坡场地，与传统剪切仪测试结果进行对比。结果表明：首级法向应力可等于或稍大于初始法向应力σ0；法向应力增量Δs与临塑应力σf与初始法向应力σ0之间存在(σ0–σf)/ Δs =4.0～4.5的关系，可指导Δs 取值；当法向位移与时间关系曲线趋于水平、法向位移速率趋于0时，固结稳定，据此可确定土体固结时间；根据剪应力与剪切位移关系曲线，可直观地判断土体所受应力状态，指导剪切力施加；新仪器与传统剪切仪相比，测试的抗剪强度指标可靠，而后者所测黏聚力值c 很小，甚至为负值。4.5 m深度处剪切板压入土体和剪切过程的数值模拟表明：法向应力介于法向位移曲线的线性变形阶段时，土体可有效固结。剪切破坏时，剪切板附近土体产生明显错动，形成条状塑性破坏带，并逐渐形成上下贯通的塑性破坏带。A new type of electronically controlled borehole shear test apparatuswas developed to aim at the shortcomings of traditional borehole shear apparatus

such as difficulty in controlling theshear rate

large test error

and the value of test parameters relying onexperience. The structure

testing principles and methods of the new apparatuswere expounded. To test the stability of the new apparatus

the new apparatuswas applied to the landslide site and compared with the test results of thetraditional shearing apparatus. Some results are obtained as follows. Thenormal stress of the first stage can be equal to or slightly greater than theinitial normal stress σ0. The relationship between normal stress increment Ds and plastic stress σf

the initial normal stress σ0 is (σ0–σf)/ Δs =4.0-4.5

which can guidethe value of Δs. When the normal displacement vs. time curve tendsto be the horizontal and the normal displacement rate tends to be 0

theconsolidation is stable

and the soil consolidation time can be determinedaccordingly. According to the curves of shear stress vs. shear displacement

the stress state of the soil can be judged intuitively

thereby guiding theexerting of shear force. Compared with the traditional borehole shear test apparatus

the new instrument can obtain more reliable strength index values

while thecohesion value c measured by the traditional apparatus is very small oreven negative. At the depth of 4.5 m

the numerical simulation of the shearplate being pressed into the soil and the shear process shows that the soil canbe effectively consolidated when the normal stress is in the linear deformationstage of the normal displacement curve; the soil near the shear plate isdislocated

forming a strip-shaped plastic failure zone

and graduallydeveloping into a plastic failure zone through an upper and lower when shearfailure occurs.