土工承载比（CBR）试验。（T0134-93）

Geotechnical bearing ratio (CBR). (T0134-93)

实验目的及适用范围

Purposes and applicable ranges

1.       本试验适用于在规定的试筒内制试件后，对各种土和路面基层，底基层材料进行承载比试验。

This test is applicable for making specimens in specified test tube which are used for carrying on bearing tests of various kinds of soils and materials of pavements and subbase.

2.       试样的最大粒径宜控制在25mm以内，最大不得超过38mm。

    The maximum particle size should be controlled within 25-38mm

试验仪器与设备

Instruments and equipments

本试验采用的仪器设备主要有：击实筒，电子秤，贯入杆，路面材料强度仪，百分表，试件顶面上的多孔板，多孔底板，以及水槽，滤纸。

The Instruments and equipments mainly applied in this test are: the compaction cylinder, electronic scale, penetration rod, and pavement material strength tester, dial gauge, the perforated plate on the top of specimen, the multi-orifice substrate, water tank and filter paper.

试样的制备

Sample preparation

本试验试样的制备参照《公路土工试验规程》中的（T0131-93）进行制备。

The test specimens were prepared according to "test methods of soils for Highway Engineering" (T0131-93) 

试验步骤

Test procedures

1.       在试件制成后，取下试件顶面的破残滤纸，放上一张好滤纸并在上面安装多孔板，在多孔板上加四块荷载板。

When the specimens are prepared, remove the broken filter paper from the top surface of the specimen, and replace a new one on the top surface of the specimen and then add four loading plates on the perforated plate.

2.       用拉杆将模具拉紧，安装百分表，并读取初读数。

Tense the mould with the tie bar, install the dial indicator and read the initial indication.

3.       向槽内放水，使水自由浸到试件的顶部和底部，在泡水期间，槽内水面应该保持在试件顶面以上大约25mm，通常试件要泡水四昼夜。

Pour the water into the tank; make the water freely dipped into the top and bottom of the specimens. During the soaking period, the water surface should be about 25mm higher than the top surface of specimen. Usually the specimens are soaked for four days.

4.       泡水结束后，读取试件上百分表的中读数，计算试件膨胀量。

After soaking, read the indication of the dial indicator and calculate the swell capacity of the specimen

5.       从水槽中取出试件，倒出试件顶面的水，擦去试筒表面的自由水，卸去负压荷载和多孔板，底板和滤纸，并称量质量以计算试件的湿度和密度的变化。

Take the specimen out of the tank; pour out the water of the top specimen surface. Wipe the free water on the surface of the cylinder and discharge the negative pressure load and perforated plate, substrate and filter paper. And then weigh the mass which in order to calculate the variation of the humidity and density of specimen.

6.       将泡水后的试件放到路面材料强度仪的升降台上，调整仪器，使贯入杆与试件顶面全面接触。在贯入杆周围放置四块荷载板。

Put the soaked specimens on the lifting platform of the pavement material strength tester, then regulate the instrument to make the penetration contact well with the top surface of specimen. Place four load plates around the penetration rod.

7.       先在贯入杆上施加45N荷载预压，然后装上百分表，并将测裂和测变形的百分表的指针都调整至0点。

Preload 45N on the penetration rod, and then install the dial indicator and adjust the pointers of the dial indicator which are measuring crack and deformation to zero.

8.       加荷，使贯入杆以1-1.25mm/min 的速度压入试件，在百分表整读数时，读取贯入量，如20,40,60时的读数，读数时注意，使贯入量为250×mm时，能有五个以上的读数，因此，测裂器内的第一个读数应是贯入量的30×左右。

Loading, press the penetration rod into the specimen at a speed of 1-1.25mm/min, read the quantity of penetration when the dial indicator reading is integer, such as the penetration quantities when the dial indicator reading is 20,40and 60. pay attention to it that there are more than 5 readings when the penetration quantity is 250×mm . Therefore, the first reading of the crack measurement device should be 30× of the quantity of penetration.

数据处理

Data processing

以单位压力p为横坐标，贯入量l为纵坐标，绘制pl曲线，图中，曲线1是适合的，曲线2开始段是凹曲线，需要进行修正，修正时，在变曲率点引一曲线与纵坐标交于O’点，O’点即为修正后的原点。

Set the unit pressure P as abscissa, penetration quantity L as the ordinate and draw the PL curve. In the diagram, curve 1 is suitable while curve 2 is sag vertical curve in the beginning which needs to be modified. When modifying, lead a curve from the variable curvature point and meet the ordinate at point O’ which is the modified original point.

1.       按下式进行承载比计算，一般采用贯入量为2.5mm时的单位压力与标准压力之比作为材料的承载比，如贯入量为5mm时的承载比大于2.5mm时的承载比，则试验要重做，如重做结果仍然如此，则采用5mm时的承载比。

贯入量为2.5mm时的承载比（CBR）:

                         CBR=

式中：CBR—承载比，%；

      P—单位压力，Kpa.

贯入量为5mm时的承载比（CBR）

Calculate the bearing ratio by the following formula; generally take the ratio of unit pressure and standard pressure of which the penetration quantity is 2.5mm as bearing ratio. If the bearing ratio of which the penetration quantity is 5mm is larger than the one of which the penetration quantity is 2.5mm, the test should be repeated. If the redo results is still so, then take the bearing ratio when the penetration quantity is 5mm as the final result.

  The bearing ratio when the penetration quantity is 2.5mm: CBR=

  In this formula: CBR—bearing ratio, %

                P—unit pressure, Kpa

  The bearing ratio when the penetration quantity is 5mm: CBR=

第二篇：土的承载力(CBR)试验报告