China highway engineering

Application status of testing instruments

Text/Zhan Vice President of Shaanxi Senior Experts Association

At present, there are 100 kinds of highway engineering test instruments used in China.

In material and structure test research, project self-inspection, project supervision and project acceptance, etc.

It is the product of the combination of nondestructive testing and photoelectron technology, and plays an important role in engineering test.

The development of modern experimental detection technology such as human body detection has played an important role.

analysis of existing circumstance

These test instruments, whether made in China or imported, can be fully loaded.

Meet the basic accuracy requirements, and most instruments are simple to operate. Some instruments are still available.

Multi-function and strong applicability, such as multi-function compactor, soil and asphalt.

The production of compacted samples of the mixture can be applied. At the same time, there is a high-tech instrument.

A certain number, such as infrared rangefinder, laser profiler, etc. , but its scale is not large. straight

Because of these characteristics, these test instruments will be used for a long time in the future.

It still applies.

Judging from the current use situation, the existing highway engineering test instruments are basically

It can meet the requirements, but there are also some problems.

Some testing instruments and technologies can no longer meet the needs of highway development.

Exhibition requirements

There are few kinds of pavement test instruments in China, and some of them are still relatively backward. For example, people

Beckman pavement deflectometer is familiar to scientists and is the most important instrument for evaluating pavement strength.

Musical instrument. It has been more than 40 years since 1964 was introduced from Canada.

Historically, it has made important contributions to the highway construction in China. But for semi-rigid base asphalt

With the rapid development of pavement, the radius of deflection influence has changed from 15m in 1960s.

7O-80 s to 25 million. According to our measurement, the current has an effect on its deflection.

The radius requirement can reach 5m. Although its measuring arm has been improved to 3.6 meters, it still

The fulcrum will fall into the deflection basin, and the deviation value will reduce the total rebound deflection.

1/4— 1/5, the measured data is distorted. If the measuring arm is extended again, it will not be used. still

There are eight-wheel road roughness measuring instruments, but there are also problems such as large error, low efficiency and many instruments.

Heavy and inconvenient to carry.

There are few cement pavements in China, and the research on its test and detection technology and instruments is not enough.

Many problems are common. For example, I measured the strength of cement concrete pavement.

Scientists have been using "drilling coring method", which is a damage measurement method. Although it can

The determination of compressive strength of cement concrete pavement is intuitive, but the junction of pavement is destroyed.

Structure. Because the concrete filled after drilling can not be consistent with the original state. After water seepage, it will

Will further expand the damaged surface. In addition, although the cement concrete rebound instrument adopts Jane

However, due to the great influence of concrete surface hardening degree, the measured data are far from each other.

Large deviation affects the test results.

In the aspect of subgrade detection, the ring knife method is used to determine the compaction degree. This method is simple and convenient.

Low cost. It has been used ever since. Because the dry density method is used, it needs to be removed

Moisture, generally on-site alcohol drying method, takes about 15 minutes, which is very inefficient:

Moreover, for humus soil, it will burn humus and cause weightlessness, which will seriously affect the accuracy.

In desert highway engineering, due to loose sand, it is easy to cause heavy particles under vibration.

New issue. Therefore, the volume of the sand sample in the annular cutter obtained by the hammering method increases.

When the dry density decreases, the measured degree of compaction is smaller. According to Yulin Expressway in Shaanxi Province,

The compaction degree is about small 12 percentage points.

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There are adaptability problems in imported test instruments.

According to the actual situation of our country, the highway engineering test instruments applicable abroad

Conditions. Some may not work. For example, a reflective laser road roughness tester.

The principle is to measure the smoothness of the road surface by receiving the laser reflected by the road surface. developed

Turf is planted on both sides of the national expressway without soil separation. The road surface is clean, instruments.

It can be used universally, but in China, its use faces great limitations. Chinese

The expressway pavement is relatively clean, so it is suitable to use reflective laser tester: it is only class II.

There are tractors and other agricultural vehicles on the pavement below the road, especially the three-grade asphalt pavement.

On the road, the road surface is very dirty, which affects the reflection of laser light. The reflection type cannot be used.

Laser measuring instrument.

development prospect

The highway construction in China is developing at an unprecedented speed, which is not only a project.

The engineering scale is large, the technology is difficult and the quality requirement is high, which is very important for the test and detection.

The work puts forward higher requirements than "satisfying the status quo". Used for highway engineering test detection.

I have several simple views on the development trend of measuring instruments: First, the integration of optics, mechanics and electronics.

Chemical detection instruments such as laser pavement detectors will be widely used, thus changing.

Good at the shortcomings of current subgrade and pavement detection instruments; Second, nondestructive measurement will greatly

Improve the detection level: Third, "joint vehicle measurement" can shorten the measurement time.

High detection efficiency and safety. Fourth, "highway remote sensing detection" will open the public in China.

A new road detection method. Introducing high technology into the field of road detection will greatly improve.

The overall level of highway inspection.