However, there are many buildings in the construction of masonry are often given reserved holes do not place lintels, some reserved oversized, some stay too small, and some reserved too high and low, so that the entire unit The dimensions are not uniform, so that in the later installation of the meter box box, the electrical installer will have to make a hole that is not reserved by himself. If there is no space reserved, he must repair it; the box for each unit is required. The installation must be uniform in size. Therefore, the results are: 1. Waste of construction materials; 2. Loss of work; 3. Large impact on the wall structure; 4. Construction waste; 5. Acceptance of the main structure. We are often caught in construction, but this problem is still inevitable, can not solve the fundamental problem, it has become a difficult problem for masonry engineering to affect the electrical installation, to completely solve this problem, it is recommended that: From the design drawings for a thorough solve. It is like a window hole in the basement and bathroom. Why are these window holes in none of the numerous building groups and numbers, and none of them leaked? There is not a size phenomenon that is not normal or high or low. Why can't we learn from them? Compared to the reserved holes in electrical distribution boxes, it is able to bend and stretch. Leakable construction, the reason I think it is still a thorough improvement in drawings and construction plans, can not follow the old design habits, we have to integrate with WT0, to solve some of the architectural problems of architectural design and The detailed plan for the construction of the bottom of the construction shall ensure that the reserved holes of the electrical equipment in the masonry construction shall be initiative and standardized and reserved for construction.

(Continued on page 630, the principle of conservation of momentum and energy in the process of rigid body collision is used. The piling formula method is most popular with the engineering news formula and the Hailey piling formula.

(2) Penetration penetration method, abbreviated as 捶 penetration method. It refers to slamming the pile top with different falling distance from low to high with a certain quality of weight, and measuring the slamming force of the pile top Qd with a force sensor. The degree of penetration measured by the dial gauge is measured by each penetration, and through the analysis of the test results, the defects of the pile are determined and the bearing capacity of the single pile is determined.

(3Smith wave equation method, set the pile as a one-dimensional elastic pile, between the pile and soil in accordance with the Newtonian viscous body and the ideal elastic body model, the sacral, alluvial block, pad, pile pad, pile, etc. are discretized into a series of units to obtain the discrete The difference equations of the system were used to obtain the pile driving response curve. According to the measured penetration, the soil suction coefficient was taken into account to determine the ultimate bearing capacity of the pile.

(4Case method, that is, the wave equation semi-empirical analysis method, according to the stress wave theory, can simultaneously analyze the pile integrity and pile-soil system bearing capacity.

(5 wave equation fitting method, CAPWAP method, is a reasonable method that is widely used at present.

(6) The static method SlamamiC, its significance lies in prolonging the impact force action time (~100mS, making it more close to the static load test state, but this method is costly, theoretical analysis and field tests still need to further embankment height.

Among them, the wave equation semi-empirical analysis method (CASE method) and the wave equation fitting analysis method (CAPWAP method) are two commonly used high-strain dynamic test piles. Their field test methods and test systems are identical. By ramming the impact pile heads, a stress wave that propagates down the pile body and a certain pile-soil displacement are generated. Accelerometers and special tool strain gauges symmetrically mounted on the pile top record the acceleration and strain under the action of the shock wave and pass through. The long-line cable is transmitted to the pile-based dynamic tester; the corresponding bearing capacity is then obtained using different principles.

2.1.2 Features of High Strain Dynamic Testing Methods In general, high strain dynamic testing has the following features: (1) The detection accuracy meets the requirements and the results are more complete. The PS curve, the single pile bearing capacity, and the high strain test pile method for embankments can not only provide the above data, but also evaluate the quality of the pile and the distribution curve of the pile body resistance. The bearing capacity measured by the two methods The error is within 10%. (2Test equipment is light. Test piles with a bearing capacity of 1400T, the equipment used for static load tests weighs 65 tons, and the certificate beam is more than 20 meters long. It brings great difficulties to the entrance and exit, and the high-strain equipment is only 12T. It can be transported into the field.(3) The test cost is low. Generally speaking, the static test budget cost is about 100,000 yuan per pile, while the high strain method is about 10,000 yuan, and the high strain method is only for the static load test cost. 1/10.(4) The testing time is short.Comparing with the inspection speed, the static load test of a pile needs to be completed in 3 to 5 days, while the high strain method can perform on-site inspection of dozens of piles in only one day.

At present, the main methods for the integrity detection of piles include low-strain dynamic test piles, sonic wave transmission, and core drilling.

With the continuous development of high-intensity measurement technology, people's understanding of the application of wave theory in the field of pile foundation testing has become more and more in-depth. As a result, low-strain testing technology has emerged. Since the concept of Sonic Integrity Testing was introduced in the Institute of TN0IBBC in the Netherlands in 1965, the low-strain test technology has been developed for more than 30 years. The low strain-rate measurement of piles is based on the application of lower excitation energy to the pile top. Cause the slight vibration of the pile body and the surrounding soil. At the same time, the instrument measures and records the vibration velocity and acceleration of the pile top, and uses wave theory or mechanical impedance theory to analyze the recorded results, so as to test the pile foundation construction quality and determine the pile For example, the integrity of the body, the prediction of pile bearing capacity, etc. The low-strain method has the advantages of rapidness, simplicity, economy, practicality, etc., on the other hand, there are problems in the testing pile area, high-frequency interference problems of large-diameter piles, and rock-socketing The pile problem, at the same time, through a large number of dynamic and static comparison tests in engineering practice, found that the results obtained by using this method to calculate the bearing capacity of a single pile is not accurate, and the static load test results have a greater deviation, so the low strain is generally only suitable for the pile Integrity testing.There are many methods for the low-strain method of pile movement measurement, such as reflection wave method, mechanical impedance method, dynamic parameter method, The following describes the reflection wave method.

The basic principle of the low-strain reflected wave method is to strike the top of a pile with force, apply a certain amount of energy to the pile, make a stress wave in the pile, and use special equipment to receive, detect and analyze the stress wave at the pile top. The process of transmission in the body can analyze the integrity of the pile foundation.

The reflected wave method uses wave propagation in the pile body to conform to the wave theory. Wave theory can be used to derive the wave equation, and then the wave equation can be solved to solve the engineering problem. However, the wave equation derived from the wave theory and propagating in the pile is a three-dimensional equation. It is difficult to solve. In practical projects, since the length of the pile buried in the ground is much greater than its diameter, this method assumes that the pile is a continuous elastic one-dimensional homogenous rod and does not consider the pair of soil around the pile.

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