Hanzhong Settlement Observation Standard Price Settlement Observation Point Wholesale Price

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　　Hanzhong Settlement Observation Standard Price Settlement Observation Point Wholesale Price

　　Layout of work base points and observation point markers

　　The working base point (hereinafter referred to as the base point) is the benchmark point for settlement observation, which should be established according to the requirements of the settlement measurement plan and network layout principles of the project. The settlement measurement plan should be formulated based on the layout characteristics of the project and the environmental conditions on site. Based on work experience, it is generally recommended to set up three base points around high-rise buildings, with a distance of 50m to 100m from the building. The base point can utilize existing and stable buried stone points and wall base leveling points, or set wall base leveling points on buildings with stable foundations and long construction time in the area. If the above conditions are not met in the area, the base point can be buried in a place with good concealment, good visibility, and safety according to the corresponding requirements. The base points set up are strictly prohibited from use until their stability is determined. Therefore, the height difference between the base points should be measured every time to determine whether they are relatively stable, and the base points should be regularly measured in conjunction with high-level benchmarks far away from the building to verify their own stability.

　　Settlement observation points should be comprehensively considered based on factors such as the shape, structure, geological conditions, and pile shape of the building, and should be placed in locations that can sensitively reflect changes in building settlement. It is generally installed at the corners of buildings, in locations with significant differential settlement, in sections with significantly different geological conditions, and on both sides of settlement cracks. When burying, pay attention to the reliable connection between the observation point and the building, so that the changes in the observation point can truly reflect the changes in the building. And based on the floor plan design drawings of the building, draw a settlement observation point layout diagram to determine the location of the settlement observation points. A fixed observation route should be established between the working point and the settlement observation point, and marker posts should be made at the instrument installation station and transfer point to ensure that each observation follows a unified route.

　　The cycle and measurement process of settlement observation

　　The period of settlement observation should reflect the settlement deformation law of buildings. Settlement observation of buildings (structures) has strict time constraints, especially observation must be carried out on time, otherwise the original data of settlement observation cannot be obtained, resulting in incomplete observation results. The retesting of other stages must be carried out regularly according to the progress of the project, without missing or supplementing the measurement, only in this way can accurate settlement conditions or patterns be obtained. It is generally believed that buildings built on sandy soil layers have mostly completed their settlement during construction, while buildings built on clay soil layers have only a partial settlement during construction, and therefore, the settlement period is variable. Based on work experience, during the construction phase, the frequency of observation should be higher. Generally, the observation period is determined by 3 days, 7 days, or 15 days, or by increasing the number of layers and loads. The specific observation period should depend on the foundation and loading during the construction process. When temporarily suspending work, observation should be conducted once during the suspension and once again during the resumption of work to check the changes in building settlement during the suspension period. This serves as a basis for determining whether the method and frequency of settlement observation should be adjusted after resuming work. After completion, the frequency of observation can be reduced, depending on the type of foundation soil and the magnitude of settlement rate. Generally, there are different periods such as one month, two months, three months, six months, and one year. Whether the settlement has entered a stable stage should be determined by the relationship curve between settlement amount and time. For key observation and scientific research projects, if the settlement in each of the last three observation cycles is not more than twice the measurement error, it can be considered as entering the stable stage. For settlement observation in general engineering, if the settlement rate is less than 0.01-0.04mm/d, it can be considered as entering the stable stage, and the specific value should be determined according to the compressibility of the foundation soil in each region.

　　According to the prepared settlement measurement plan and the determined observation period, observation should be carried out in a timely manner after the observation point is stable. Generally, high-rise buildings have one or several underground structures, and observation should start from the foundation. Settlement observation points (temporary) should be buried at the designed positions on the longitudinal and transverse axes of the foundation (foundation edge). Observation can only be carried out after the temporary observation points are stable. The elevation values of the settlement observation points observed are the basis for comparison in future observations, and their accuracy requirements are very high. N2 level precision leveling instruments are generally used for measurement, and each observation point elevation should be observed twice during the same period. Comparing the observation results, if the height difference between the same observation points does not exceed ± 0.5mm, we can consider the observed data to be reliable. As the structure rises one level, temporary observation points are moved up one level and observed until+0.00, and then observation points are buried according to regulations (for ease of observation, observation points can be set at+500mm). Then, every layer of construction is retested until completion.

　　When conducting settlement observations during the stages of pile driving, excavation of foundation pits, and continuous layering of the upper part after the completion of the foundation, it is necessary to record various factors that affect settlement changes and anomalies, such as the construction progress, increased load capacity, warehouse loading and unloading tonnage, building inclination cracks, etc., for each observation. After weekly observation, the observation data should be promptly organized to calculate the settlement amount, settlement difference, average settlement amount and settlement velocity of the observation point for the current period. If there is an abnormal change in the amount of change, the client should be immediately notified to provide a basis for taking preventive measures, and the number of observations should be appropriately increased.

　　On the other hand, observations of different periods should follow the principle of "five determinations". The so-called "five determinations" refer to the benchmark points, base points, and settlement observation points on the observed object that are commonly used as the basis for settlement observation, and the points should be stable; The instruments and equipment used should be stable; Observers need to be stable; The environmental conditions during observation should be basically consistent; The observation route, mirror position, program, and method should be fixed. The above measures objectively ensure that the subjective uncertainty of observation errors is minimized as much as possible, so that the measured results have a unified tendency; Can ensure the comparability between each retest result and the observation result, making the observed settlement more accurate.

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