How to Install a Mobile Toilet Underground

Before installing a mobile toilet underground, foundation treatment must be completed first. Typically, a concrete pre-fabricated base or a steel chassis is used as the supporting structure. The specific steps and precautions are as follows:

I. Foundation Type Selection and Construction

1. Concrete Pre-fabricated Base
   The concrete base needs to be poured on-site at the installation location, with its dimensions determined according to the weight, size, and design requirements of the mobile toilet. Before pouring, the site must be cleared and the soil compacted to ensure tight contact between the base bottom and the soil. After pouring, curing is required, usually waiting for 7-14 days (the specific time is affected by the ambient temperature). Only after the concrete strength reaches the design standard (generally not lower than C25) can the upper structure be installed. This method is suitable for areas with complex geological conditions and low soil bearing capacity, providing more stable support.

2. Steel Chassis
   If the soil bearing capacity of the site is high and the terrain is flat, a steel chassis can be directly used as the foundation. The chassis needs to be fixed to the ground with anchor bolts, and the bolt spacing must comply with design specifications (usually 500-800mm) to ensure a firm connection between the chassis and the ground. Before installing the steel chassis, the flatness of the ground must be checked, with an error controlled within ±5mm to avoid structural deformation of the toilet due to uneven ground.

II. Environmental Assessment Before Installation

1. Terrain Flatness
   A laser level or a water level must be used to detect the slope of the site to ensure that the slope of the installation area does not exceed 2%. If the terrain has significant undulations, leveling must be carried out by backfilling earth or cutting the foundation to avoid inconvenience in use or structural damage to the toilet due to tilting.

2. Soil Bearing Capacity
   The soil bearing capacity must be detected through static cone penetration or standard penetration tests to ensure that it is not lower than 150kPa (the specific value must be adjusted according to the weight of the toilet). If the soil bearing capacity is insufficient, foundation reinforcement must be carried out, such as replacing with gravel, driving wooden piles, or using reinforced concrete pile foundations.

3. Underground Pipeline Distribution
   Before installation, contact the municipal department to obtain underground pipeline maps and use a detector to confirm the locations of cables, water pipes, gas pipelines, etc. During construction, pipeline areas must be avoided. If avoidance is impossible, the toilet location must be adjusted or trenchless technology (such as pipe jacking) must be used to protect the pipelines.

III. Precautions During Installation

1. Level Calibration of the Base and Chassis
   During installation, a level must be used to repeatedly calibrate the levelness of the base or chassis to ensure that the error does not exceed ±2mm. If a concrete base is used, the levelness must be re-measured regularly during the curing period to avoid tilting due to concrete shrinkage.

2. Fastening of Connectors
   When connecting the toilet body to the foundation, high-strength bolts (such as Grade 8.8) must be used and anti-loosening adhesive must be applied to ensure a firm connection. If the toilet is designed with seismic requirements, rubber shock absorbers must be installed at the connections.

3. Connection of the Drainage System
   For underground installation, the direction of the drainage pipeline must be planned in advance to ensure smooth connection between the toilet's sewage outlet and the municipal sewer network or septic tank. The drainage pipeline must be made of PVC or HDPE material, with a slope of not less than 1% to avoid blockage or odor.