WO2019109633A1 - 用于桩土界面抗剪强度原位测试的方法与对称式直剪仪 - Google Patents

用于桩土界面抗剪强度原位测试的方法与对称式直剪仪 Download PDF

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WO2019109633A1
WO2019109633A1 PCT/CN2018/093998 CN2018093998W WO2019109633A1 WO 2019109633 A1 WO2019109633 A1 WO 2019109633A1 CN 2018093998 W CN2018093998 W CN 2018093998W WO 2019109633 A1 WO2019109633 A1 WO 2019109633A1
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shear
shearing
box
spring
pile
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PCT/CN2018/093998
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English (en)
French (fr)
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苏栋
黄俊杰
明海燕
陈锐
陆钊
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深圳大学
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/24—Investigating strength properties of solid materials by application of mechanical stress by applying steady shearing forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0025—Shearing
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/003—Generation of the force
    • G01N2203/0032—Generation of the force using mechanical means
    • G01N2203/0033—Weight
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0298—Manufacturing or preparing specimens
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0676—Force, weight, load, energy, speed or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0682—Spatial dimension, e.g. length, area, angle
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
    • Y02A10/23—Dune restoration or creation; Cliff stabilisation

Definitions

  • the invention relates to a symmetrical straight shear instrument, in particular to a method for in-situ testing of shear strength of a pile-soil interface and a symmetrical straight shear instrument.
  • the direct shear test was first used by Alexandre Collin for slope stability studies more than 100 years ago. At present, the development and research technology of indoor direct shearing instrument is relatively mature. In addition to the conventional small direct shearing instrument, some large-scale direct shearing instruments have been developed at home and abroad. The shape of the shearing box is various and the size is different. The direct shearing instrument has many styles, but the basic principle is the same. The specimens are loaded into the shearing box, and the horizontal shearing force is applied under different vertical pressures ⁇ to shear the specimens. Shearing to damage occurs on the horizontal plane between the cut boxes, and the shear stress ⁇ at the time of failure is obtained, and the internal friction angle ⁇ and the cohesive force c of the soil are determined according to the Mohr-Coulomb law.
  • the direct shear instrument can be divided into two types: strain control type and stress control type.
  • the former is to control the rate of shear displacement by elastic steel ring deformation; the latter is to control the rate of shear stress applied by the weight of the lever, and then measure The corresponding shear displacement is obtained.
  • the more advanced direct shearing instrument is a large constant stiffness interface cyclic shearing instrument.
  • the large constant stiffness interface cyclic shearing instrument uses a spring to provide normal constant stiffness, and realizes the lower shearing through the variable frequency motor and the stroke switch. The reciprocating cyclic shearing motion of the box.
  • the constant stiffness pile-soil interface shearing instrument not only avoids the size effect problem existing in the traditional direct shearing instrument, but also keeps the shearing area constant during the shearing process.
  • the manufacturing cost of direct shears has gradually increased, and the maintenance and maintenance costs of the instruments have become increasingly expensive.
  • the instruments are too large to be tested indoors and cannot be performed. Measurement of the shear strength of the pile-soil interface at the site.
  • the present invention provides a method for in-situ testing of shear strength of a pile-soil interface and a symmetrical straight shear.
  • the invention provides a symmetrical straight shear instrument for in-situ testing of shear strength of pile-soil interface, comprising a bracket provided with two symmetrically distributed shearing devices, the shearing device comprising shearing a box, a fan-shaped distributed normal force providing mechanism that applies a normal force to the soil sample in the shear box, a shear displacement measuring mechanism that measures a shear displacement of the shear box, and a shear to the shear box a shearing weight, wherein the shearing box is provided with a soil sample placing cavity for placing a soil sample and a shearing box upper cover for controlling the soil sample placing cavity, the cutting box upper cover and the The shearing box forms a moving pair, and the fixed end of the fan-shaped distributed normal force providing mechanism is connected to the bracket through a spring bracket, and the force applying end of the fan-shaped distributed normal force providing mechanism is connected with the upper cover of the shearing box
  • the shear displacement measuring mechanism is disposed at a top of the shear box
  • the fan-shaped distributed normal force providing mechanism includes an annular slider and a spring, one end of the spring is connected to the spring bracket, and the other end of the spring is connected to the annular slider.
  • the annular slider is coupled to the upper cover of the shear box.
  • the spring and the annular slider are evenly spaced along the circumferential direction of the upper cover of the cutting box.
  • a spring washer is disposed between the spring and the annular slider, and the spring bracket is provided with a spring guiding rod, and the spring is sleeved on the spring guiding rod.
  • the spring guide rod is provided with a limit nut for adjusting the amount of deformation of the spring, and the spring bracket is connected to the bracket by a fixing bolt.
  • a low resistance sealing strip is disposed between the upper cover of the shearing box and the shearing box.
  • the shear displacement measuring mechanism includes a dial gauge bracket and a first dial gauge fixed to the dial gauge bracket, the first dial gauge rod and the shearing The top of the box is in contact with a second dial gauge on the spring bracket, and the rod of the second dial gauge is in contact with the upper lid of the shear box.
  • the shearing box is provided with a pulley block near the end of the pile body.
  • the portion of the bracket adjacent to the pile body is provided with a pulley.
  • the invention also provides a method for in-situ testing of shear strength of pile-soil interface, and the following steps are performed by using the symmetrical straight shear instrument:
  • the geotechnical knife tool When measuring with the symmetrical straight shear tester, the geotechnical knife tool is used to separate the pile side test soil from the surrounding soil body, first roughing according to the size of the shear box, and then placing the shear box on the soil sample, and installing The bracket ensures that the soil samples on both sides are on the same horizontal surface and compresses the upper cover of the shear box, thereby realizing the purpose of applying normal stress to the soil sample.
  • the pile is used.
  • the vertical shear force is applied uniformly by the weight, and the shear stress is applied in the same amount of 8%-10% of the estimated maximum load. After each stage of the shear load is applied for a minute, the application is applied.
  • the next-stage shear load is terminated when the shear deformation increases sharply or the shear displacement reaches 1/10 of the side length of the test piece;
  • k is the stiffness coefficient of the spring
  • the unit is: N/mm, and n is the number of springs
  • A is the area of the sample
  • the unit is: m 2
  • the volume change of the soil sample during the shearing process is obtained by the reading of the shear displacement measuring mechanism
  • the average shear stress ⁇ during the shearing of the specimen is calculated according to the following formula:
  • A is the area of the sample, the unit is: m 2 , F is the weight of the weight, the unit is: kN, G is the weight unit of the shear box: kN;
  • the invention has the beneficial effects that the normal force is applied by the fan-shaped distributed normal force providing mechanism, and the normal force source or the loading device is not needed, and the normal force is applied by the fan-shaped distributed normal force providing mechanism through the center of the sample. Ensure that the normal force of each point at the pile-soil interface is the same, pointing to the center of the circle, so that the shearing surface is evenly stressed, avoiding the eccentric load of the sample and causing deviation of the test results; less components, light weight and simple assembly It is easy to use in the field.
  • Figure 1 is a schematic illustration of a plan view of a symmetrical straight shear meter of the present invention.
  • Figure 2 is a schematic illustration of the front view of a symmetrical straight shear meter of the present invention.
  • FIG. 3 is a schematic view of a fan-shaped distributed normal force providing mechanism of a symmetrical straight shear instrument of the present invention.
  • a symmetrical straight shear instrument for in-situ testing of shear strength of pile-soil interface includes a bracket 1 on which two symmetrically distributed shearing devices are disposed.
  • the shearing device comprises a shearing box 11, a fan-shaped distributed normal force providing mechanism for applying a normal force to the soil sample 100 in the shearing box 11, and a shear displacement for measuring the shear displacement of the shearing box 11.
  • a measuring mechanism and a weight 16 for applying a shearing force to the shearing box 11 wherein the shearing box 11 is provided with a soil sample placing cavity for placing the soil sample 100 and a shearing device for controlling the soil sample placing cavity Cutting the upper cover 5, the shearing box upper cover 5 and the shearing box 11 form a moving pair, and the fixed end of the fan-shaped distributed normal force providing mechanism is connected to the bracket 1 through the spring bracket 2, a force applying end of the fan-shaped distributed normal force providing mechanism is coupled to the shear box upper cover 5, the shear displacement measuring mechanism is disposed at the top of the shearing box 11, the weight 16 and the cutting The bottom of the box 11 is connected.
  • the sector-shaped distributed normal force providing mechanism includes an annular slider 8 and a spring 7, one end of which is connected to the spring holder 2, and the other end of the spring 7 is The annular slider 8 is connected, and the annular slider 8 is connected to the upper cover 5 of the cutting box.
  • the spring 7 and the annular slider 5 are evenly spaced along the circumferential direction of the upper cover 5 of the cutting case.
  • a spring washer 9 is disposed between the spring 7 and the annular slider 5.
  • the spring bracket 2 is provided with a spring guide 12, and the spring 7 is sleeved on the spring. On the guide bar 12.
  • the spring guide rod 12 is provided with a limit nut 6 for adjusting the deformation amount of the spring 7
  • the spring bracket 2 is connected to the bracket 1 by a fixing bolt 3 .
  • a low-resistance sealing strip 15 is disposed between the upper cover 5 of the shearing box and the shearing box 11.
  • the shear displacement measuring mechanism includes a dial gauge bracket 13 and a first dial gauge 14 fixed to the dial gauge bracket 13, and the first dial gauge 14 is measured.
  • the rod is in contact with the top of the shearing box 11, and the spring holder 2 is provided with a second dial gauge 4, and the rod of the second dial gauge 4 is in contact with the cutting box upper cover 5.
  • the shear box 11 is provided with a pulley block 10 near the end of the pile body 200.
  • a portion of the bracket 1 adjacent to the pile body 200 is provided with a pulley 17.
  • the pile side test soil is separated from the surrounding soil by a tool such as a geotool, first roughed according to the size of the shear box, and then the shear box 11 is placed on the soil sample 100, and the bracket 1 is adjusted. Fixing bolts 3, ensuring that the shear specimens on both sides are on the same horizontal plane, and the spring washer 9 connected to the spring 7 is placed on the annular slider 8 on the upper cover 5 of the shear box, and then the dial gauge bracket is mounted. 13 and the first percentile 14.
  • the pile body 200 is used as a shear box lower box, and the shear force in the vertical direction is uniformly applied by the weight 16, and the shear stress is applied in an equal amount of 8%-10% of the estimated maximum load, and the shear load is applied per stage. After 5 minutes, the next level of shear load is applied, and the test can be terminated when the shear deformation increases sharply or the shear displacement reaches 1/10 of the side length of the test piece.
  • the readings of the first percent meter 14, the second dial meter 4, and the mass of the weight 16 were recorded, and the normal stress and the average shear stress acting on the soil sample 100 were calculated from these readings.
  • the compression amount x of the spring can be calculated, and the normal load N acting on the soil sample 100 is calculated by the following formula:
  • k is the stiffness coefficient of the spring 7 (unit: N/mm) and n is the number of springs 7.
  • A is the area of the sample (unit: m 2 ), and the volume change of the soil sample during the shearing process can be obtained by reading the second percentage table 4.
  • the average shear stress ⁇ during the shearing of the specimen is calculated according to the following formula:
  • A is the area of the sample (unit: m 2 )
  • F is the weight of the weight (unit: kN)
  • G is the weight of the shear box (unit: kN).
  • the ⁇ -s relationship curve is drawn, and the peak value of the shear stress ⁇ on the curve is taken as the shear strength.
  • the shear stress corresponding to the shear displacement of 4 mm is Shear strength.
  • the invention provides a shear strength test method and a symmetric direct shear tester for the shear strength test of the in-situ pile-soil interface, and is suitable for the constant stiffness of the interface between the large-diameter pile and the soil (or mud) at the site.
  • the shear resistance under the condition and the shear displacement during the shearing process are determined; the instrument is simple, easy to carry, simple to operate, accurate, economical and practical, and can perform symmetric shear test on two samples at the same time, stability Good, applicability, and good prospects for promotion and application.
  • the invention provides a symmetrical straight shearing device, wherein the normal load is carried out by a fan-shaped distributed spring loading, that is, by adjusting the compression amount of the spring 7, the application of different normal loads can be achieved, and at the same time, the application of each spring 7 is ensured.
  • the force is consistent with the interface normal direction.
  • the invention provides a shear strength testing method and a symmetric direct shearing instrument, which have the following advantages:
  • Two sets of shear tests can be performed at the same time to improve the working efficiency of the direct shear and shorten the test time.

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Abstract

一种用于桩土界面抗剪强度原位测试的对称式直剪仪，包括支架（1），所述支架（1）上设有两个对称分布的剪切装置，所述剪切装置包括剪切盒（11）、向所述剪切盒（11）内的土样（100）施加法向力的扇形分布式法向力提供机构、测量所述剪切盒（11）剪切位移的剪切位移测量机构和向所述剪切盒（11）施加剪切力的砝码（16），以及一种用于桩土界面抗剪强度原位测试的方法。采用通过利用扇形分布式法向力提供机构施加均匀分布的法向力，无需外接压力源或加荷设备，采用通过试样中心的扇形分布式法向力提供机构进行法向力的施加，保证界面处各点的法向力大小相同，均指向圆心，使得剪切面受力均匀，避免试样受偏心受荷而使试验结果存在偏差。

Description

用于桩土界面抗剪强度原位测试的方法与对称式直剪仪 技术领域
本发明涉及对称式直剪仪，尤其涉及一种用于桩土界面抗剪强度原位测试的方法与对称式直剪仪。
背景技术
直剪试验最早在100多年前被Alexandre Collin用于边坡稳定研究。目前，室内直剪仪的开发和研制技术比较成熟，除了常规的小型直剪仪外，国内外均研制出了一些大型直剪仪，剪切盒形式繁多，尺寸大小不一。直剪仪样式繁多，但基本原理相同，都是将试样装填入剪切盒内，分别在不同的垂直压力σ下，施加水平剪切力进行剪切，使试样在上、下剪切盒之间的水平面上发生剪切至破坏，得到破坏时的剪切应力τ，根据摩尔-库仑定律确定土的内摩擦角φ和黏聚力c。
目前，直剪仪可分为应变控制式和应力控制式两种，前者是通过弹性钢环变形控制剪切位移的速率；后者则是通过杠杆用砝码控制施加剪应力的速率，进而测出相应的剪切位移。随着技术手段的进步，目前较为先进的直剪仪为大型恒刚度界面循环剪切仪，大型恒刚度界面循环剪切仪采用弹簧提供法向恒刚度，通过变频电机及行程开关实现下剪切盒的往复循环剪切运动。恒刚度桩-土界面剪切仪不仅避免了传统直剪仪中存在的尺寸效应问题，而且在剪切过程中始终保持剪切面积恒定。但随着直剪试验仪器的日益复杂化和精密化，直剪仪的制造成本逐渐增加，仪器的保养和维护 费用变得日益昂贵，另外，仪器尺寸过大，仅能进行室内试验，无法进行工地现场桩土界面的抗剪强度的测量。
发明内容
为了解决现有技术中的问题，本发明提供了一种用于桩土界面抗剪强度原位测试的方法与对称式直剪仪。
本发明提供了一种用于桩土界面抗剪强度原位测试的对称式直剪仪，包括支架，所述支架上设有两个对称分布的剪切装置，所述剪切装置包括剪切盒、向所述剪切盒内的土样施加法向力的扇形分布式法向力提供机构、测量所述剪切盒剪切位移的剪切位移测量机构和向所述剪切盒施加剪切力的砝码，其中，所述剪切盒设有放置土样的土样放置腔体和控制所述土样放置腔体的剪切盒上盖，所述剪切盒上盖与所述剪切盒形成移动副，所述扇形分布式法向力提供机构的固定端通过弹簧支架与所述支架连接，所述扇形分布式法向力提供机构的施力端与所述剪切盒上盖连接，所述剪切位移测量机构设置在所述剪切盒的顶部，所述砝码与所述剪切盒的底部连接。
作为本发明的进一步改进，所述扇形分布式法向力提供机构包括环形滑块和弹簧，所述弹簧的一端与所述弹簧支架连接，所述弹簧的另一端与所述环形滑块连接，所述环形滑块与所述剪切盒上盖连接。
作为本发明的进一步改进，所述弹簧与所述环形滑块沿所述剪切盒上盖的周向间隔均匀设置。
作为本发明的进一步改进，所述弹簧、环形滑块之间设有弹簧垫片，所述弹簧支架上设有弹簧导杆，所述弹簧套设在所述弹簧导杆上。
作为本发明的进一步改进，所述弹簧导杆上设有调节所述弹簧变形量的限位螺母，所述弹簧支架通过固定螺栓与所述支架连接。
作为本发明的进一步改进，所述剪切盒上盖与所述剪切盒之间设有低阻密封胶条。
作为本发明的进一步改进，所述剪切位移测量机构包括百分表支架和固定在所述百分表支架的第一百分表，所述第一百分表的测杆与所述剪切盒的顶部接触，所述弹簧支架上设有第二百分表，所述第二百分表的测杆与所述剪切盒上盖接触。
作为本发明的进一步改进，所述剪切盒靠近桩身的端部设有滑轮组。
作为本发明的进一步改进，所述支架靠近桩身的部分设有滑轮。
本发明还提供了一种用于桩土界面抗剪强度原位测试的方法，采用所述的对称式直剪仪进行以下步骤：
使用所述的对称式直剪仪测量时，采用土工刀工具将桩侧试验土体与周围土体分开,先按剪切盒大小进行粗修,然后将剪切盒放置于土样上，安装支架，确保两侧的土样处于同一水平面上，压缩剪切盒上盖，从而实现对土样施加法向应力的目的，待垂直压力稳定、垂直变形达到每小时不超过0.05mm后，以桩身作为剪切盒下盒，通过砝码均匀施加竖直方向的剪切力，剪应力按预估最大荷载的8％-10％分级等量施加,每级剪切荷载施加分钟后，再施加下一级剪切荷载,当剪切变形急剧增加或剪切位移达到试件边长的1/10时时终止试验；
在实验过程中，记录剪切位移测量机构的读数以及砝码的质量，然后计 算作用在土样上的法向应力和平均剪应力；
计算弹簧的压缩量x,通过下式计算出作用在土样上的法向荷载N：
N＝n·k·x
其中，k为弹簧的刚度系数，单位为：N/mm，n为弹簧的根数；
由法向荷载N计算土样上的平均法向应力σ n：
Figure PCTCN2018093998-appb-000001
其中，A为试样的面积，单位为：m 2，通过剪切位移测量机构的读数得到剪切过程中土样的体积变化；
试样剪切过程中的平均剪应力τ根据下式计算：
Figure PCTCN2018093998-appb-000002
其中，A为试样的面积，单位为：m 2，F为砝码的重量，单位为：kN，G为剪切盒的重量单位为：kN；
以剪应力为纵坐标，剪切位移为横坐标，绘制τ-s关系曲线，取曲线上的剪应力τ的峰值作为抗剪强度，无峰值时，取剪切位移4mm所对应的剪应力为抗剪强度；
以试样的峰值抗剪强度τ为纵坐标，法向应力σ n为横坐标，绘制σ n-τ关系曲线，直线的倾角为桩土界面的外摩擦角，纵坐标上的截距为粘聚力。
本发明的有益效果是：利用扇形分布式法向力提供机构施加法向力，无需外接压力源或加荷设备，采用通过试样中心的扇形分布式法向力提供机构进行法向力的施加，保证桩-土界面处各点的法向力大小相同，均指向 圆心，使得剪切面受力均匀，避免试样受偏心受荷而使试验结果存在偏差；组件少，质量轻便，组装简单，便于野外现场使用。
附图说明
图1是本发明一种对称式直剪仪的俯视方向的示意图。
图2是本发明一种对称式直剪仪的主视方向的示意图。
图3是本发明一种对称式直剪仪的扇形分布式法向力提供机构的示意图。
具体实施方式
下面结合附图说明及具体实施方式对本发明作进一步说明。
如图1至图3所示，一种用于桩土界面抗剪强度原位测试的对称式直剪仪，包括支架1，所述支架1上设有两个对称分布的剪切装置，所述剪切装置包括剪切盒11、向所述剪切盒11内的土样100施加法向力的扇形分布式法向力提供机构、测量所述剪切盒11剪切位移的剪切位移测量机构和向所述剪切盒11施加剪切力的砝码16，其中，所述剪切盒11设有放置土样100的土样放置腔体和控制所述土样放置腔体的剪切盒上盖5，所述剪切盒上盖5与所述剪切盒11形成移动副，所述扇形分布式法向力提供机构的固定端通过弹簧支架2与所述支架1连接，所述扇形分布式法向力提供机构的施力端与所述剪切盒上盖5连接，所述剪切位移测量机构设置在所述剪切盒11的顶部，所述砝码16与所述剪切盒11的底部连接。
如图1至图3所示，所述扇形分布式法向力提供机构包括环形滑块8和弹簧7，所述弹簧7的一端与所述弹簧支架2连接，所述弹簧7的另一端 与所述环形滑块8连接，所述环形滑块8与所述剪切盒上盖5连接。
如图1至图3所示，所述弹簧7与所述环形滑块5沿所述剪切盒上盖5的周向间隔均匀设置。
如图1至图3所示，所述弹簧7、环形滑块5之间设有弹簧垫片9，所述弹簧支架2上设有弹簧导杆12，所述弹簧7套设在所述弹簧导杆12上。
如图1至图3所示，所述弹簧导杆12上设有调节所述弹簧7变形量的限位螺母6，所述弹簧支架2通过固定螺栓3与所述支架1连接。
如图1至图3所示，所述剪切盒上盖5与所述剪切盒11之间设有低阻密封胶条15。
如图1至图3所示，所述剪切位移测量机构包括百分表支架13和固定在所述百分表支架13的第一百分表14，所述第一百分表14的测杆与所述剪切盒11的顶部接触，所述弹簧支架2上设有第二百分表4，所述第二百分表4的测杆与所述剪切盒上盖5接触。
如图1至图3所示，所述剪切盒11靠近桩身200的端部设有滑轮组10。
如图1至图3所示，所述支架1靠近桩身200的部分设有滑轮17。
一种用于桩土界面抗剪强度原位测试的方法，通过对称式直剪仪进行抗剪强度测试：
使用仪器测量时，采用土工刀等工具将桩侧试验土体与周围土体分开,先按剪切盒大小进行粗修,然后将剪切盒11放置于土样100上，安装支架1、调节固定螺栓3，确保两侧的剪切试样处于同一水平面上，并且，与弹簧7连接的弹簧垫片9置于剪切盒上盖5上的环形滑块8上，然后安装百分表支架 13和第一百分表14。调节限位螺母6，以使得弹簧7压缩剪切盒上盖5，从而实现对土样100施加法向应力的目的，待垂直压力稳定、垂直变形达到相对稳定(每小时不超过0.05mm)后，以桩身200作为剪切盒下盒，通过砝码16均匀施加竖直方向的剪切力，剪应力按预估最大荷载的8％-10％分级等量施加,每级剪切荷载施加5min后，再施加下一级剪切荷载,当剪切变形急剧增加或剪切位移达到试件边长的1/10时时可终止试验。在实验过程中，记录第一百分表14、第二百分表4的读数以及砝码16的质量，并通过这些读数计算作用在土样100上的法向应力和平均剪应力。
根据弹簧导杆12上的刻度可以计算得到弹簧的压缩量x,通过下式计算出作用在土样100上的法向荷载N：
N＝n·k·x
其中，k为弹簧7的刚度系数(单位为：N/mm)，n为弹簧7的根数。
由法向荷载N可以计算土样100上的平均法向应力σ n：
Figure PCTCN2018093998-appb-000003
其中，A为试样的面积(单位为：m 2)，通过第二百分表4的读数可得剪切过程中土样的体积变化。
试样剪切过程中的平均剪应力τ根据下式计算：
Figure PCTCN2018093998-appb-000004
其中，A为试样的面积(单位为：m 2)，F为砝码的重量(单位为：kN)，G为剪切盒的重量(单位为：kN)。
以剪应力为纵坐标，剪切位移为横坐标，绘制τ-s关系曲线，取曲线上的剪应力τ的峰值作为抗剪强度，无峰值时，取剪切位移4mm所对应的剪应力为抗剪强度。
以试样的峰值抗剪强度τ为纵坐标，法向应力σ n为横坐标，绘制σ n-τ关系曲线，用直线拟合曲线，直线的倾角为桩土界面的外摩擦角，纵坐标上的截距为粘聚力。
本发明提供的一种抗剪强度测试方法与对称式直剪仪，用于原位桩土界面抗剪强度测试，适用于在工地现场对大直径桩与土(或泥皮)界面在恒刚度条件下的抗剪切力和剪切过程中的剪切位移进行测定；仪器设备简单、携带方便、操作简单、结果准确、经济实用，可同时对两个试样进行对称剪切试验，稳定性好，适用性强，具有良好的推广应用前景。
本发明提供的一种对称式直剪仪，法向荷载采用扇形分布式弹簧加载的方式，即可以通过调节弹簧7的压缩量来达到施加不同法向荷载，并同时保证每根弹簧7施加的作用力与界面法向一致，通过对不同法向荷载下的试样施加竖直向的推力进行剪切，得出每个试样的剪应力-剪切位移曲线和试样的σ-τ关系曲线，然后用最小二乘法得出土体的抗剪强度参数c、
Figure PCTCN2018093998-appb-000005
并确定其抗剪强度特性。
本发明提供的一种抗剪强度测试方法与对称式直剪仪，具有以下优点：
(1)组件少，质量轻便，组装简单，便于野外现场使用。
(2)利用扇形分布式弹簧施加法向力，无需外接压力源或加荷设备，采用通过试样中心的弹簧组进行法向力的施加，保证桩-土界面处 各点的法向力大小相同，且均指向圆心，使得剪切面受力均匀，避免试样偏心受荷而使试验结果存在偏差；而采用弹簧恒刚度加载，试验机理更接近真实的桩-土应力场。
(3)以桩身200作为剪切下盒，可以在现场直接对桩土界面的抗剪强度进行精确测试，无需对桩和土进行取样。
(4)可同时进行两组剪切试验，提高直剪仪的工作效率，缩短试验的时间。
(5)通过采用(替换)不同曲率半径的弹簧支架2，可适用于不同桩径的桩土界面测试。
以上内容是结合具体的优选实施方式对本发明所作的进一步详细说明，不能认定本发明的具体实施只局限于这些说明。对于本发明所属技术领域的普通技术人员来说，在不脱离本发明构思的前提下，还可以做出若干简单推演或替换，都应当视为属于本发明的保护范围。

Claims (10)

  1. 一种用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：包括支架，所述支架上设有二个对称分布的剪切装置，所述剪切装置包括剪切盒、向所述剪切盒内的土样施加法向力的扇形分布式法向力提供机构、测量所述剪切盒剪切位移的剪切位移测量机构和向所述剪切盒施加剪切力的砝码，其中，所述剪切盒设有放置土样的土样放置腔体和控制所述土样放置腔体的剪切盒上盖，所述剪切盒上盖与所述剪切盒形成移动副，所述扇形分布式法向力提供机构的固定端通过弹簧支架与所述支架连接，所述扇形分布式法向力提供机构的施力端与所述剪切盒上盖连接，所述剪切位移测量机构设置在所述剪切盒的顶部，所述砝码与所述剪切盒的底部连接。
  2. 根据权利要求1所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述扇形分布式法向力提供机构包括环形滑块和弹簧，所述弹簧的一端与所述弹簧支架连接，所述弹簧的另一端与所述环形滑块连接，所述环形滑块与所述剪切盒上盖连接。
  3. 根据权利要求2所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述弹簧与所述环形滑块沿所述剪切盒上盖周向间隔均匀设置。
  4. 根据权利要求2所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述弹簧、环形滑块之间设有弹簧垫片，所述弹簧支架上设有弹簧导杆，所述弹簧套设在所述弹簧导杆上。
  5. 根据权利要求2所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述弹簧导杆上设有调节所述弹簧变形量的限位螺母，所述弹簧支架通过固定螺栓与所述支架连接。
  6. 根据权利要求2所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述剪切盒上盖与所述剪切盒之间设有低阻密封胶条。
  7. 根据权利要求2所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述剪切位移测量机构包括百分表支架和固定在所述百分表支架的第一百分表，所述第一百分表的测杆与所述剪切盒的顶部接触，所述弹簧支架上设有第二百分表，所述第二百分表的测杆与所述剪切盒上盖接触。
  8. 根据权利要求1所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述剪切盒靠近桩身的端部设有滑轮组。
  9. 根据权利要求1所述的用于桩土界面抗剪强度原位测试的对称式直剪仪，其特征在于：所述支架靠近桩身的部分设有滑轮。
  10. 一种用于桩土界面抗剪强度原位测试的方法，其特征在于：采用如权利要求2所述的对称式直剪仪进行以下步骤：
    使用所述的对称式直剪仪测量时，采用土工刀工具将桩侧试验土体与周围土体分开,先按剪切盒大小进行粗修,然后将剪切盒放置于土样上，安装支架，确保两侧的土样处于同一水平面上，通过弹簧变形施加法向压力压缩剪切盒上盖，从而实现对土样施加法向应力的目的，待垂直压力稳定、 垂直变形达到每小时不超过0.05mm后，以桩身作为剪切盒下盒，通过砝码均匀施加竖直方向的剪切力，剪应力按预估最大荷载的8％-10％分级等量施加,每级剪切荷载施加分钟后，再施加下一级剪切荷载,当剪切变形急剧增加或剪切位移达到试件边长的1/10时终止试验；
    在实验过程中，记录剪切位移测量机构的读数以及砝码的质量，然后计算作用在土样上的法向应力和平均剪应力；
    计算弹簧的压缩量x,通过下式计算出作用在土样上的法向荷载N：
    N＝n·k·x
    其中，k为弹簧的刚度系数，单位为：N/mm，n为弹簧的根数；
    由法向荷载N计算土样上的平均法向应力σ n：
    Figure PCTCN2018093998-appb-100001
    其中，A为试样的面积，单位为：m 2，通过剪切位移测量机构的读数得到剪切过程中土样的体积变化；
    试样剪切过程中的平均剪应力τ根据下式计算：
    Figure PCTCN2018093998-appb-100002
    其中，A为试样的面积，单位为：m 2，F为砝码的重量，单位为：kN，G为剪切盒的重量单位为：kN；
    以剪应力为纵坐标，剪切位移为横坐标，绘制τ-s关系曲线，取曲线上的剪应力τ的峰值作为抗剪强度，无峰值时，取剪切位移4mm所对应的剪应力为抗剪强度；
    以试样的峰值抗剪强度τ为纵坐标，法向应力σ n为横坐标，绘制σ n-τ关系曲线，用直线拟合该曲线，直线的倾角为土与桩界面的外摩擦角，直线在纵坐标上的截距为粘聚力。
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CN110261254A (zh) * 2019-07-22 2019-09-20 华中农业大学 一种原位土壤参数测量仪及测量方法
CN110361272A (zh) * 2019-08-09 2019-10-22 广西科技大学 一种直剪及复合受剪的试验装置
CN113686697A (zh) * 2021-08-18 2021-11-23 中国电建集团华东勘测设计研究院有限公司 野外粗粒土干湿循环条件下直接剪切试验装置及其使用方法
CN113866019A (zh) * 2021-09-30 2021-12-31 建材桂林地质工程勘察院有限公司 一种适用于变尺寸裂隙土的直剪试验装置
CN114354375A (zh) * 2021-11-25 2022-04-15 河海大学 一种超轻黏土的塑性沉陷测量装置和使用方法及应用
CN114414403A (zh) * 2022-01-26 2022-04-29 中国矿业大学 一种实现采动应力梯度下岩石剪切的实验装置及方法
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CN112525728B (zh) * 2020-11-23 2023-09-08 西安建筑科技大学 一种大尺寸加筋土抗剪强度测试设备及试验方法
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CN113324854B (zh) * 2021-05-31 2022-07-22 西华大学 一种土样强度测试装置及其实验方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003121328A (ja) * 2001-10-10 2003-04-23 Building Research Institute せん断試験治具
US7392708B2 (en) * 2005-05-06 2008-07-01 The Boeing Company Apparatus and method of measuring shear strain of thick adhesive bondlines
CN106370528A (zh) * 2016-08-21 2017-02-01 浙江科技学院 便携式岩体结构面直剪试验仪
CN106556542A (zh) * 2016-11-21 2017-04-05 南京大学 一种土石混合体直剪松弛试验装置及试验方法
CN106769539A (zh) * 2016-12-02 2017-05-31 中国地质大学（武汉） 一种考虑渗流‑应力‑化学耦合的岩土体剪切流变仪
CN108106949A (zh) * 2017-12-04 2018-06-01 深圳大学 用于桩土界面抗剪强度原位测试的方法与对称式直剪仪
CN207570938U (zh) * 2017-12-04 2018-07-03 深圳大学 一种用于原位桩土界面抗剪强度测试的对称式直剪仪

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1254669C (zh) * 2004-05-09 2006-05-03 中国科学院地质与地球物理研究所 双杠杆加载原位土直剪仪
CN101105433B (zh) * 2007-07-26 2011-01-12 河海大学 便携式现场和室内两用直剪试验仪及其取样测试方法
CN103487329B (zh) * 2013-09-25 2016-01-20 深圳大学 用于土壤与结构面的力学测试仪及其测试方法
CN103558096B (zh) * 2013-11-04 2016-01-20 中国地质科学院地质力学研究所 带有自动数据采集系统的岩土体原位直剪试验装置及方法
CN104792629B (zh) * 2015-04-29 2018-01-19 深圳大学 一种手持式常刚度环剪仪及其使用方法
CN104897321B (zh) * 2015-06-24 2016-08-24 潍坊学院 一种预制开口混凝土管桩桩身内壁剪应力测试方法
CN104931361B (zh) * 2015-06-26 2017-08-11 青岛理工大学 一种敞口混凝土管桩桩土界面剪切模拟试验方法
CN106124341B (zh) * 2016-06-20 2019-02-19 三峡大学 一种土岩界面现场直剪试验试样制备及试验装置
CN106442135A (zh) * 2016-10-11 2017-02-22 深圳大学 一种软粘土土体原位测试装置及测试方法
CN106644765A (zh) * 2017-01-09 2017-05-10 浙江大学 一种用于室内试验桩土界面的环剪仪及检测方法
CN107271297B (zh) * 2017-06-08 2020-11-03 西北大学 一种用于测定饱和黄土-泥岩接触面的原位剪切实验仪

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2003121328A (ja) * 2001-10-10 2003-04-23 Building Research Institute せん断試験治具
US7392708B2 (en) * 2005-05-06 2008-07-01 The Boeing Company Apparatus and method of measuring shear strain of thick adhesive bondlines
CN106370528A (zh) * 2016-08-21 2017-02-01 浙江科技学院 便携式岩体结构面直剪试验仪
CN106556542A (zh) * 2016-11-21 2017-04-05 南京大学 一种土石混合体直剪松弛试验装置及试验方法
CN106769539A (zh) * 2016-12-02 2017-05-31 中国地质大学（武汉） 一种考虑渗流‑应力‑化学耦合的岩土体剪切流变仪
CN108106949A (zh) * 2017-12-04 2018-06-01 深圳大学 用于桩土界面抗剪强度原位测试的方法与对称式直剪仪
CN207570938U (zh) * 2017-12-04 2018-07-03 深圳大学 一种用于原位桩土界面抗剪强度测试的对称式直剪仪

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110261254A (zh) * 2019-07-22 2019-09-20 华中农业大学 一种原位土壤参数测量仪及测量方法
CN110261254B (zh) * 2019-07-22 2024-04-09 华中农业大学 一种原位土壤参数测量仪及测量方法
CN110361272A (zh) * 2019-08-09 2019-10-22 广西科技大学 一种直剪及复合受剪的试验装置
CN110361272B (zh) * 2019-08-09 2024-03-15 广西科技大学 一种直剪及复合受剪的试验装置
CN113686697A (zh) * 2021-08-18 2021-11-23 中国电建集团华东勘测设计研究院有限公司 野外粗粒土干湿循环条件下直接剪切试验装置及其使用方法
CN113866019A (zh) * 2021-09-30 2021-12-31 建材桂林地质工程勘察院有限公司 一种适用于变尺寸裂隙土的直剪试验装置
CN113866019B (zh) * 2021-09-30 2024-04-09 建材桂林地质工程勘察院有限公司 一种适用于变尺寸裂隙土的直剪试验装置
CN114354375A (zh) * 2021-11-25 2022-04-15 河海大学 一种超轻黏土的塑性沉陷测量装置和使用方法及应用
CN114544387A (zh) * 2022-01-10 2022-05-27 广城建设集团有限公司 一种具有斜向剪切试验功能的干湿循环试验装置
CN114414403A (zh) * 2022-01-26 2022-04-29 中国矿业大学 一种实现采动应力梯度下岩石剪切的实验装置及方法
CN114414403B (zh) * 2022-01-26 2023-11-28 中国矿业大学 一种实现采动应力梯度下岩石剪切的实验装置及方法

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