A high anchoring force variable rate static sounding penetration system suitable for hard soil

Abstract

The application discloses a high anchoring force variable rate static sounding penetration system suitable for hard soil, wherein in the strong freezing anchoring system, low-temperature circulating liquid pipelines are arranged on the blades of the screw anchor and are connected with a low-temperature circulating refrigeration system, and a counterforce steel frame is connected to the upper portion of the screw anchor; the low-temperature circulating refrigeration system adopts a liquid ammonia freezing system to carry out refrigeration, so as to form a strong freezing anchoring area in the soil layer around the screw blade and provide the penetration counterforce of the hard soil site. In the hydraulic rate adaptive penetration system, a hydraulic rate adapter and a penetration propeller are connected through a shaft coupling rod and drive a probe rod on which a static sounding probe is installed; after the intelligent pressure rate sensing and adjusting system identifies that the static sounding probe has entered the hard soil layer according to the real-time collection of the cone tip resistance, the sidewall friction resistance and the penetration speed in the process of the penetration of the soil layer by the static sounding probe, the penetration rate of the sounding probe is controlled to be 10 ‑4 ~10 ‑6 cm / s through the hydraulic rate adapter, so that the low strain rate penetration is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a penetration system for geotechnical engineering in-situ testing, in particular to a static sounding penetration system suitable for hard soil sites such as frozen soil. BACKGROUND

[0002] With the rapid development of economy, the process of urbanization and industrialization is accelerating, and the area and volume of urban circles are becoming larger and larger. Special hard soil sites such as frozen soil, weathered rock and solidified soil frequently appear in the conventional engineering construction process. Therefore, it is of great significance to effectively and accurately obtain the geological survey data and engineering property parameters of hard soil sites such as frozen soil for the design and treatment of the related regional foundation.

[0003] Hard soil sites usually use drilling sampling and indoor testing to obtain and analyze engineering property parameters, but sampling indoor testing has problems such as large sample disturbance, discontinuous data, and time and labor consuming. Modern static sounding technology is a kind of in-situ testing technology for site engineering characteristics, which has the advantages of high precision, rich data and convenient operation, and is widely used in geotechnical engineering in-situ testing. Therefore, using static sounding technology to detect the engineering characteristics of hard soil sites such as frozen soil can effectively overcome the existing problems of hard soil site parameter acquisition and analysis.

[0004] It should be noted that modern static sounding technology is usually applied to sites such as cohesive soil, silty soil and sandy soil, and the device has certain limitations when applied to hard soil layers such as frozen soil, weathered rock and solidified soil. Common problems include probe skewing, penetration difficulty, unstable penetration rate, insufficient reaction force and other problems. It is difficult to stably obtain accurate data of the physical and mechanical properties of hard soil layers, it is difficult to achieve standard requirements of constant speed and uniform speed static sounding test, and it cannot avoid the influence of strain rate on the strength parameters of hard soil.

[0005] The penetration rate of static sounding test is an important reason affecting the accuracy of in-situ strength parameter measurement data of hard soil sites such as frozen soil. Fast penetration and slow penetration will have different degrees of influence on the measured in-situ strength parameters. The compressive strength of hard soil has rate sensitivity, which is related to strain rate and medium type. It is reflected in the different ratio of dynamic compressive strength to static compressive strength λ. Based on the statistical analysis results, taking weathered rock as an example, the strain rate range of static loading is ε' < 5 × 10 -4 s -1 ; the strain rate range of medium strain rate loading is 5 × 10 -4 s -1 < 10 2 s -1Regression fitting of data from the static and quasi-dynamic regions revealed that under static loading, λ remained near 1.00, close to a constant; under medium strain rate loading, λ and strain rate followed a power function distribution:

[0006] λ is the ratio of dynamic compressive strength to static compressive strength; ε' is the strain rate. Based on the sensitivity of compressive strength to strain rate, three ranges can be defined: ε' < 10. -4 s -1 When the sensitivity is poor; ε'>10 -3 s -1 Sensitivity is highest at 10. -4 s -1 <ε'<10 -3 s -1 At that time, it was quite sensitive.

[0007] In summary, to achieve continuous, high-precision in-situ testing using a static cone penetration test system in hard soil sites such as frozen soil, it is necessary to address sufficient reaction force conditions and an effective real-time control system for the penetration rate. Therefore, there is an urgent need to propose a static cone penetration test system with high anchoring force and variable rate suitable for hard soil sites such as frozen soil. Summary of the Invention

[0008] Purpose of the invention: To address the shortcomings of existing static cone penetration testing (CPPT) techniques, which cannot be effectively tested in hard soil sites such as frozen soil due to the lack of real-time control of reaction force conditions and effective penetration rate, this invention provides a high-anchorage variable-rate static cone penetration testing system suitable for hard soil sites such as frozen soil, thereby improving the level of testing and detection of engineering characteristics in hard soil sites.

[0009] Technical solution: A high-anchorage variable-rate static cone penetration system suitable for hard soil, including a strong freezing anchorage system, a hydraulic rate-adaptive penetration system, and a probe rod equipped with a static cone penetration probe.

[0010] The high-strength freezing anchoring system includes a high-strength steel spiral anchor, a low-temperature circulating refrigeration system, and a reaction steel frame. Low-temperature circulating liquid pipes are distributed on the lower spiral blades of the high-strength steel spiral anchor. The low-temperature circulating liquid pipes are connected to the low-temperature circulating refrigeration system through the hollow rod at the top of the high-strength steel spiral anchor. The reaction steel frame is connected to the hollow rod at the top of the high-strength steel spiral anchor.

[0011] The hydraulic rate adaptation penetration system comprises an intelligent pressure rate sensing and adjusting system, a hydraulic rate adapter, a penetration propeller, a probe rod stabilizing device and a rigid support; the hydraulic rate adapter and the penetration propeller are connected through a shaft coupling and fixed on the rigid support; the probe rod stabilizing device is fixed at the bottom of the rigid support, a probe rod with a static sounding probe installed thereon passes through the probe rod stabilizing device, and the penetration propeller is connected with the probe rod; the hydraulic rate adapter is connected with the intelligent pressure rate sensing and adjusting system through a cable.

[0012] The low-temperature circulating refrigeration system is used for refrigeration by adopting a liquid ammonia freezing system after the fine steel spiral ground anchor is rotated and penetrated into the earth, a strong frozen anchoring area is formed in the soil layer around the lower spiral blade of the fine steel spiral ground anchor, and a counterforce for penetration is provided for a hard soil site;

[0013] The intelligent pressure rate sensing and adjusting system is used for real-time collection of the cone tip resistance, the sidewall friction resistance and the penetration speed of the static sounding probe during penetration into the soil layer, discrimination of whether the hard soil layer is entered, and control of the hydraulic rate adapter to make the penetration rate of the static sounding probe be 10 -4 ~ 10 -6 cm / s after the hard soil layer is entered, so that low strain rate penetration is realized.

[0014] Further, the outer diameter of the upper hollow rod of the fine steel spiral ground anchor is 50 mm, the rod wall thickness is 5 mm, the outer diameter of the lower spiral blade is 300-500 mm, and the blade thickness is 30 mm.

[0015] Further, the low-temperature circulating liquid pipes are distributed in an equidistant spiral shape on the surface of the lower spiral blade of the fine steel spiral ground anchor, and the pipe spacing is 50 mm.

[0016] Further, the material of the lower spiral blade is a low-temperature resistant stainless steel material.

[0017] Further, the material of the probe rod stabilizing device is a polyoxymethylene rubber material.

[0018] Further, the intelligent pressure rate sensing and adjusting system discriminates whether the hard soil layer is entered according to the real-time collection of the cone tip resistance, the sidewall friction resistance and the penetration speed of the static sounding probe during penetration into the soil layer according to a pre-calibration model.

[0019] Further, the counterforce steel frame is connected to the hollow rod at the upper part of the fine steel spiral ground anchor through a buckle type lock head.

[0020] Beneficial effects: The strong frozen anchoring technology is combined with the spiral anchor rod and the liquid ammonia circulating freezing technology in the application, the soil around the spiral blade is frozen, the anchoring area and the anchoring strength are improved, and the counterforce range of the static sounding penetration technology is increased.

[0021] The present application adjusts the penetration rate of the static sounding probe in the hard soil site such as frozen soil in real time through the hydraulic intelligent rate adaptation penetration system, so that the penetration rate is controlled at 10 -4 ~10 -6 cm / s, significantly eliminates the strain rate induced influencing factors in the static sounding penetration process, and realizes low strain rate penetration. By precisely controlling the probe penetration rate, more accurate and more standard hard soil layer parameters are obtained.

[0022] The present application provides a powerful in-situ testing tool for evaluating the engineering characteristics of hard soil sites such as frozen soil in geotechnical engineering survey practice, which is fast, economical, easy to operate, high in accuracy, and has important engineering significance. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a structural schematic diagram of the system of the present application;

[0024] Figure 2 is a structural schematic diagram of the strong frozen anchoring system in the system of the present application. DETAILED DESCRIPTION

[0025] The present application will be further explained below in combination with the drawings.

[0026] As Figure 1 shown, a high anchoring force variable rate static sounding penetration system suitable for hard soil provides super-high counterforce support through a strong frozen anchoring system 1, and is matched with a hydraulic rate adaptation penetration system 2 to realize the low strain rate penetration ability of the static sounding probe in the hard soil site such as frozen soil.

[0027] The strong frozen anchoring system 1 includes a high-steel spiral ground anchor 3, a low-temperature circulating refrigeration system 4, and a counterforce steel frame 8. The lower spiral blades 5 of the high-steel spiral ground anchor 3 are distributed with low-temperature circulating liquid pipelines 6, the low-temperature circulating liquid pipelines 6 are connected with the low-temperature circulating refrigeration system 4 through the hollow rods 7 on the upper part of the high-steel spiral ground anchor 3, and the counterforce steel frame 8 is connected on the hollow rods 7 on the upper part of the high-steel spiral ground anchor 3 through the buckle type lock head 9.

[0028] The hydraulic rate adaptive penetration system 2 comprises an intelligent pressure rate sensing and adjusting system 10, a hydraulic rate adapter 11, a penetration pusher 12, a probe rod stabilizing device 13 and a rigid support 14. The hydraulic rate adapter 11 and the penetration pusher 12 are connected by a shaft coupling 15 and fixed on the rigid support 14. The probe rod stabilizing device 13 is fixed on the bottom of the rigid support 14, the probe rod with a static sounding probe head passes through the probe rod stabilizing device 13, and the penetration pusher 12 is connected with the probe rod. The hydraulic rate adapter 11 is connected with the intelligent pressure rate sensing and adjusting system 10 through a cable, and the intelligent pressure rate sensing and adjusting system 10 comprises a penetration pressure and rate data acquisition instrument 16, a data processing analyzer 17 and a rate adjusting software 18, which jointly control the system penetration process.

[0029] The probe rod with a static sounding probe head passes through the penetration pusher 12 and the probe rod stabilizing device 13 in sequence, the penetration pusher 12 provides penetration force after locking the probe rod, and the probe rod stabilizing device 13 adjusts the penetration inclination of the probe rod. After starting the static sounding test, the required penetration force is calculated through the penetration pressure and rate data acquisition instrument 16, the data processing analyzer 17 and the rate adjusting software 18 according to the real-time test soil layer data transmitted by the probe head, and the hydraulic transmission power in the hydraulic rate adapter 11 is adjusted to control the penetration pusher 12 locked with the shaft coupling 15, so as to provide stable pushing force for the static sounding probe rod to achieve the target penetration rate. When the rate is too slow, the inclination of the probe rod in the penetration process is ensured not to exceed the limited range through the fixing action of the probe rod stabilizing device 13.

[0030] The low-temperature circulating refrigeration system 4 is used for refrigeration by using a liquid ammonia freezing system after the fine steel spiral ground anchor 3 rotates and penetrates into the soil, so as to quickly form a strong frozen anchoring area around the lower spiral blade 5 of the fine steel spiral ground anchor 3, and provide a penetration counterforce of a hard soil site.

[0031] The intelligent pressure rate sensing and adjusting system 10 is used for real-time collection of the cone tip resistance, the sidewall friction resistance and the penetration speed of the static sounding probe head in the process of penetrating into the soil layer, and real-time adjustment of the penetration rate of the static sounding probe head in the range of 10 -4 ~10 -6 cm / s through the control of the hydraulic rate adapter 11 after entering the hard soil layer, so as to realize low strain rate penetration.

[0032] In the embodiment, the outer diameter of the upper hollow rod 7 of the fine steel spiral ground anchor 3 is 50 mm, the rod wall thickness is 5 mm, the outer diameter of the lower spiral blade 5 is 300-500 mm, and the blade thickness is 30 mm. The material of the lower spiral blade 5 is low-temperature resistant stainless steel material, the low-temperature circulating liquid pipeline 6 is distributed in an equidistant spiral shape on the surface of the lower spiral blade 5 of the fine steel spiral ground anchor 3, and the pipeline spacing is 50 mm. The material of the probe rod stabilizing device 13 is polyoxymethylene rubber material.

[0033] The system is applied to the static sounding method of hard soil site such as frozen soil, which comprises the following steps:

[0034] Step 1: Level the site, erect the system equipment, and debug the running state of each supporting system.

[0035] Step 2: Rotate the lower two steel spiral anchors 3 into the soil, start the low-temperature circulating refrigeration system 4 to circulate refrigerant ammonia in the low-temperature circulating liquid pipeline 6 on the surface of the lower spiral blade 5, and change the soil around the lower spiral blade 5 into a frozen area to enhance the anchoring area and anchoring strength of the anchor; then connect the counterforce steel frame 8 and lock it through the buckle type lock head 9.

[0036] Step 3: Connect the hydraulic rate adapter 11 to the intelligent pressure rate sensing and adjusting system 10.

[0037] Step 4: Install the static sounding probe, pass the probe rod from the probe rod stabilizing device 13, maintain the vertical state of the probe rod, and connect the probe rod with the penetration pusher 12.

[0038] Step 5: Start the hydraulic rate adapter 11 and the penetration pusher 12 to drive the probe rod to penetrate into the soil layer, and simultaneously start the intelligent pressure rate sensing and adjusting system 10 to monitor the cone tip resistance, sidewall friction resistance, and penetration rate of the static sounding probe in real time during the static sounding penetration process, and determine whether to enter the hard soil layer such as frozen soil according to the pre-calibrated model.

[0039] Step 6: After entering the hard soil layer such as frozen soil, adjust the penetration rate through the hydraulic rate adapter 11 to reduce to 10 -4 -10 -6 cm / s in real time to reduce the strain rate of the hard soil site.

[0040] Step 7: End the static sounding test, transmit the data to the computer, correct and verify the data, and obtain the engineering properties of the hard soil layer such as frozen soil after processing by professional static sounding software, and draw the geological profile of the site.

[0041] The above only describes the preferred embodiments of the present application, and it should be noted that for ordinary skilled persons in the technical field, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A high-anchorage variable-rate static cone penetration test system suitable for hard soil, characterized in that, It includes a high-strength freezing anchoring system (1), a hydraulic rate-adaptive penetration system (2), and a probe rod equipped with a static cone penetration probe; The high-strength freezing anchoring system (1) includes a steel spiral ground anchor (3), a low-temperature circulating refrigeration system (4), and a reaction steel frame (8); the lower spiral blades (5) of the steel spiral ground anchor (3) are provided with low-temperature circulating liquid pipes (6), which are connected to the low-temperature circulating refrigeration system (4) through the hollow rod (7) at the top of the steel spiral ground anchor (3), and the reaction steel frame (8) is connected to the hollow rod (7) at the top of the steel spiral ground anchor (3); The hydraulic rate-adaptive penetration system (2) includes an intelligent pressure rate sensing and adjustment system (10), a hydraulic rate adapter (11), a penetration thruster (12), a probe stabilizing device (13), and a rigid support (14); the hydraulic rate adapter (11) and the penetration thruster (12) are connected by a coupling rod (15) and fixed on the rigid support (14); the probe stabilizing device (13) is fixed at the bottom of the rigid support (14), and the probe rod with the static penetration probe is installed passes through the probe stabilizing device (13), and the penetration thruster (12) is connected to the probe rod; the hydraulic rate adapter (11) is connected to the intelligent pressure rate sensing and adjustment system (10) by a cable; The low-temperature circulating refrigeration system (4) is used to refrigerate the steel spiral anchor (3) after it rotates and penetrates into the soil using a liquid ammonia refrigeration system. This forms a strong frozen anchoring zone in the soil layer around the spiral blades (5) at the bottom of the steel spiral anchor (3), providing penetration reaction force for hard soil sites. The intelligent pressure-rate sensing and control system (10) is used to collect the cone tip resistance, sidewall friction resistance and penetration speed of the static cone penetration probe in real time during the penetration process to determine whether it has entered the hard soil layer, and after entering the hard soil layer, control the hydraulic rate adapter (11) to keep the penetration speed of the static cone penetration probe at 10 -4 ~10 -6 cm / s, thus achieving low strain rate penetration; The intelligent pressure rate sensing and adjustment system (10) determines whether it has entered the hard soil layer based on the pre-calibrated model and the real-time collection of the cone tip resistance, side wall friction and penetration speed of the static penetration probe during the penetration process.

2. The high-anchorage variable-rate static cone penetration test system for hard soil according to claim 1, characterized in that, The upper hollow rod (7) of the steel spiral anchor (3) has an outer diameter of 50 mm and a wall thickness of 5 mm. The lower spiral blade (5) has an outer diameter of 300-500 mm and a blade thickness of 30 mm.

3. The high-anchorage variable-rate static cone penetration test system for hard soil according to claim 2, characterized in that, The low-temperature circulating fluid pipes (6) are distributed in an equally spaced spiral shape on the surface of the lower spiral blades (5) of the steel spiral anchor (3), with a pipe spacing of 50 mm.

4. The high-anchorage variable-rate static cone penetration test system for hard soil according to claim 3, characterized in that, The material of the lower spiral blade (5) is low-temperature resistant stainless steel.

5. The high-anchorage variable-rate static cone penetration test system for hard soil according to claim 1, characterized in that, The probe stabilizing device (13) is made of polyoxymethylene rubber.

6. The high-anchorage variable-rate static cone penetration test system for hard soil according to claim 1, characterized in that, The reaction steel frame (8) is connected to the hollow rod (7) on the upper part of the steel spiral anchor (3) by a snap-lock head (9).

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