Several methods of subgrade compactness detection.

For the field detection of soil subgrade compactness, the methods can be divided into in-process monitoring and post-process detection. The only monitoring method in the process is intelligent compaction system method, and the rest are traditional methods, mostly after the event. Late detection is limited, time-consuming and laborious, and sampling detection can not reflect the overall compactness. If the inspection fails afterwards, the cost of rework is very high. However, the traditional methods also have certain effects for different situations. The following are the main contents of several subgrade compaction testing methods brought by Zhong Da Consulting for reference.

Intelligent compaction method

At present, on-line monitoring needs the joint action of high-precision GPS technology and compactness sensor technology to monitor the compactness during subgrade construction. However, these two technologies are also the difficulties of monitoring. At present, only intelligent compaction system successfully combines these two technologies, which can reflect the overall degree of compaction in real time.

Intelligent compaction system realizes remote compaction monitoring through the following three system modules:

1, intelligent compaction field system

(1) Intelligent Compaction Management Subsystem for Different Materials

A) Single steel wheel intelligent subgrade compaction management subsystem

B) intelligent asphalt pavement compaction management subsystem with double steel wheels

C) tire intelligent asphalt pavement compaction management subsystem

(2) Whether there is a cooperative relationship between the scale of the working face and the application scenarios.

A) single machine operation mode

B) Cluster operation cooperation mode

(3) for different customers

A) On-site intelligent compaction navigation system.

B) Real-time data acquisition system of background data analysis alarm system.

2. Data transmission system

A) Reliable GPRS data transmission subsystem between operation surface and data center

B) Intelligent data transmission subsystem between vehicles in the working face.

C) wifi data monitoring and transmission subsystem between the operation surface and the site management personnel.

3. Cloud analysis alarm system

A) after-sales cloud center data analysis subsystem

B) user cloud analysis subsystem

C) Intelligent alarm subsystem of mobile phone short message

Test method for measuring compactness by digging holes and filling sand.

Purpose and scope of application

This test is suitable for measuring the density and compactness of base (or subbase), gravel pavement and subgrade soil compaction layer of various materials in the field. However, it is not suitable for compaction test of materials with large holes or pores such as rock-filled embankments.

When measuring density and compactness by digging holes and filling sand, the following provisions shall be met:

(1) When the maximum particle size of aggregate is less than 13.2, and the thickness of test layer is less than 150mm,? 100mm small irrigation sand pipe test.

(2) When the maximum particle size of aggregate is equal to or greater than 13.2mm, but not greater than 310.5 mm, and the measured layer thickness is less than 200mm, it shall be applied? 150mm large sand filling pipe test.

Test method for determination of compactness by nuclear density hygrometer

Purpose and scope of application

(1) This method is suitable for measuring the density and water content of subgrade or pavement materials by scattering method or direct transmission method with a nuclear densitometer on site, and calculating the construction compactness.

(2) Nuclear density meter is a common method to detect the degree of compaction on site. After the instrument is calibrated according to the specified method, its test results can be used as the basis for engineering quality evaluation and acceptance. This method can detect soil, gravel, earth-rock mixture, asphalt mixture, unhardened cement concrete and other materials.

Test method for determining density by ring knife method.

This method is suitable for fine-grained soil and inorganic binder to stabilize the density of fine-grained soil. However, for fine-grained soil with stable inorganic binder, its age should not exceed 2 days, so it is suitable for compaction test during construction.

Test method for measuring compaction degree of asphalt pavement by core drilling method

The degree of compaction depends on the measured compaction density and is also related to the standard density. In some projects, Marshall test will be carried out again when the degree of compaction fails to meet the requirements and the standard density will be adjusted. As long as the standard density is made smaller, the degree of compaction will be higher. If the unqualified data are discarded at will, the compaction data of the drilling specimen will lose its value.

There is not much explanation about the methods and steps here.

Test method for determination of compaction degree by seedless densitometer

(1) This method is suitable for quickly measuring the density of asphalt mixture in each layer of asphalt pavement and calculating the construction compactness with on-site non-nuclear densitometer, but the measurement result is not suitable for evaluation, acceptance or arbitration.

The seedless densimeter is a nondestructive testing method. Because its application effect has not been fully verified, its determination results are not suitable for evaluation, acceptance or arbitration at present.

(2) The seedless densimeter can be used to detect the density of the paved asphalt pavement and asphalt mixture paving layer on site and quickly check the segregation of the mixture.

(3) Because the reliability of this detection needs to be compared and tested repeatedly, it has not been widely used in engineering quality detection, and it can only be used as an indirect detection method.

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