What issues should be considered when constructing during the rainy season?

Precautions for Construction During the Rainy Season (Excerpt from the Project Department) Precautions for Construction During the Rainy Season I. Preparation before construction in the rainy season: 1. Before the rainy season arrives, the relevant departments of the construction unit shall conduct a thorough inspection within their respective areas, check the drainage conditions at the construction site, inspect the leak prevention features of temporary facilities, repair and strengthen the existing drainage systems, and add additional drainage facilities if necessary to ensure smooth water flow. It is also necessary to prevent surface water from entering the construction site. 2. The transportation roads on site must be kept clear; the road surface should be covered with slag, gravel, or other anti-slip materials as needed, and the roadbed should be raised and reinforced if necessary. 3. Develop a construction plan for the rainy season, formulate specific measures, and arrange those projects that are not suitable for construction during the rainy season to be carried out before or after the rainy season. 4. The material warehouse should be thoroughly inspected and repaired; in particular, the area around the cement warehouse must have good drainage, ensuring that the roof does not leak, the walls do not absorb water, and the floor does not become damp. Steel should be stored in a dry place, with rain protection measures in place to prevent rusting. Waterproof and insulating materials should be stored in a dry place, away from moisture and rain. Materials left outdoors must not be submerged in water to prevent loss and waste. 5. High-rise buildings, tower cranes, and lattice frames shall be equipped with lightning protection devices in accordance with the \"Technical Specifications for Safety of Temporary Electricity Use at Construction Sites,\" and their performance should be checked regularly; any defective devices must be repaired promptly. Mixing machinery and various tools used on site should have rain shelters installed, while concrete and mortar transportation equipment should be fitted with rain covers or shields ； Based on the project conditions, prepare the necessary drainage equipment and materials. Regularly check the insulation and weather protection of the electrical and mechanical equipment’s wiring, verify that the neutral wires and grounding are in order, and install leakage protectors as required. II. Principles for construction during the rainy season: During construction, priority should be given to the foundation and structure; outdoor work should be carried out first and indoor work later. Work should continue in light rain, while it should be moved indoors during heavy rain, in order to shorten the construction period and improve economic efficiency. 1. Earthwork: ① The work area for construction during the rainy season should not be too large; it should be completed in stages, piece by piece. Important or special earthwork tasks should be finished as much as possible before the rainy season begins. ②During construction in the rainy season, technical measures must be put in place to ensure project quality and safe construction, and weather conditions should be monitored at all times. ③When excavating foundation pits, trenches, or ducts during the rainy season, attention must be paid to slope stability. If necessary, the slope gradient can be reduced appropriately or supports can be installed; during construction, regular inspections of the slopes and supports are required. ④When stacking various construction materials at the slopes of foundation pits (trenches), they should be placed at specified distances from each other. The distance between various construction machinery and the edge of the foundation pit (trench) slope should be determined based on the weight of the equipment, the support system in place for the slope, and the soil conditions; this distance must not be less than 1.5 meters. ⑤When mechanically excavating soil, workers must not enter the area where the machinery is operating to carry out cleaning or grading tasks. ⑥When excavating foundation pits (trenches) or ducts during the rainy season, it is necessary to build earth embankments around the outside of the pit (trench) or dig ditches to prevent surface water from flowing in. After the excavation of the foundation pit (trench), construction of the underground structures and installation works should be carried out promptly. During the construction process, the stability of the pit (trench) walls must be checked at all times. ⑦During fill construction, various processes such as soil extraction, transportation, laying, and compaction should be carried out sequentially. Before it rains, the filled layer should be compacted in a timely manner or its surface smoothed, and a certain slope should be created to facilitate the drainage of rainwater. 2. Masonry work: ① In rainy weather, do not use bricks and stones that are too wet to prevent mortar from flowing and affecting the quality of the masonry; when work resumes after rain, check the verticality of the masonry again. ② When working in rainy weather, it is necessary to prevent rainwater from washing away the mortar; the consistency of the mortar should be reduced appropriately, the daily construction height should not exceed 1.2 meters, and the surface of the masonry should be covered at the end of each workday. ③ Mortar should be used immediately after mixing; cement mortar or cement-based mixed mortar must be used within 2 hours and 3 hours respectively after mixing when the maximum temperature exceeds 30°C. 3. Concrete works: ① Keep track of weather forecasts in a timely manner, arrange the construction procedures for cast-in-place concrete properly, and take measures to protect it from rain and ensure proper curing. ②For projects that require continuous pouring of concrete, rain protection measures should be taken in advance. The moisture content of the aggregates should be measured regularly, and the concrete mix ratio should be adjusted accordingly. The mix ratio must be controlled strictly, as well as the slump value, to ensure the quality of the concrete. ③Strengthen the inspection of template support systems and the areas where components are stacked; the feet of such supports must be solid and secure. If necessary, increase the load-bearing area to prevent the supports from deforming, sinking, or tilting. ④During construction in the rainy season, rain protection measures should be taken; concrete should not be poured outdoors when it is raining. Concrete that is irrigated outdoors without rain is also covered promptly to prevent it from being washed away by rain. Special attention should be paid to changes in the moisture content of sand and gravel in the open storage areas; the water-cement ratio should be adjusted to ensure the strength of the concrete, and concrete trucks should be covered. ⑤To ensure there is sufficient time for pouring before the concrete begins to set, the time elapsed from the completion of concrete mixing to the end of pouring should not exceed the specified limit. When the temperature is below 25°C, for concrete of grade C30 or lower, this time limit is 2 hours ； For concrete of grade C30 and above, the time should not exceed 1.5 hours; when the temperature is above 25°C, this time should be reduced by 0.5 hours accordingly. III. Precautions for construction during the rainy season 1. Bricks that have been exposed to rain, especially those with a high moisture content, should be dried before use. 2. Masonry structures severely damaged by heavy rain and flooding should be demolished and rebuilt. 3. Appropriate measures must be taken for the newly poured concrete to prevent it from being washed away by heavy rain; otherwise, it must be inspected or treated by the relevant authorities before construction can resume. 4. After the rain, the formwork and supports should be carefully inspected, with particular attention paid to whether there is any loosening or settlement at the base of the supports, so that measures can be taken promptly. 5. The moisture content of sand and gravel used in construction after rain should be tested, so as to adjust the mix ratio promptly. 6. Reliable safeguards must be in place for the raw materials used in construction; all construction sites should have sufficient dry raw materials before the rainy season arrives, so that work can continue after the rain. It is strictly prohibited to store cement outdoors, and care must be taken to protect the raw materials from moisture and humidity. 7. On hot days, it is necessary to strengthen the curing of cast-in-place concrete; concrete made from portland cement, ordinary portland cement, or slag portland cement must be cured for at least 7 days and nights ； For concrete that contains retarding admixtures or for which water resistance is required, the curing period must be no less than 14 days. The frequency of watering should be such that the concrete remains sufficiently moist, in order to prevent cracking; if cracking occurs, use of such concrete should be prohibited in severe cases. 8. After rain, it is necessary to conduct a thorough inspection of the safety nets on the scaffolding, the foundation of the tower crane, the base of the cross-frame structure, the wind ropes, and the ground anchors. Any issues identified must be addressed promptly.

To summarize: 1) The on-site drainage facilities should be kept unobstructed； 2) Earthy subgrades in low-lying areas, areas with significant filling and excavation, and areas with poor geological conditions should avoid construction during the rainy season ； 3) During embankment construction in the rainy season, excavation, transportation, and compaction should be carried out simultaneously; each layer of fill material should have a cross-slope of 2-3%, and the loose soil laid down should be compacted tightly before it starts to rain and at the end of work ； 4) When excavating cuttings during the rainy season, it is advisable to carry out the excavation in layers, with each layer having a longitudinal slope of more than 1%. A 30 cm thick reserve should be left along the edges of the excavated slopes, which will be adjusted to the designed slope lines after the rainy season ； When excavating a cut, it is advisable to stop at a depth of 30 cm below the base surface of the subgrade, and wait until the rainy season is over before continuing to excavate to the design elevation.

The simple ones are: 1. Rain protection measures. Construction aspects, material aspects. Ensure safe construction, and the materials must not get damp from rain. 2. Prevent water from entering the construction area when it is underground. 3. When working at heights, it is essential to wear a full-body safety belt, and the belt must be secured to a firm surface.

Ensure proper drainage; prevent surface water from entering the construction site around it, and reinforce the roadbed