In recent years, the rapid socio-economic development and technological advancements in our country have accelerated urbanization, leading to the construction of numerous engineering projects. However, this growth has also been accompanied by frequent construction quality issues and safety incidents. To effectively enhance construction quality, it is imperative to conduct rigorous geotechnical investigations in accordance with relevant standards, enabling the timely identification of deficiencies and the implementation of appropriate corrective measures. As an engineer involved in this field, I have witnessed the critical role of geotechnical surveys in ensuring project safety and cost-effectiveness. This article, based on my experience and analysis, presents a comprehensive site suitability assessment for a proposed resin sand casting project. The resin sand casting process, widely used in manufacturing, requires stable foundation conditions due to the heavy machinery and structural loads involved. Therefore, a detailed geotechnical evaluation is essential to guarantee the longevity and safety of such facilities.
The resin sand casting project under consideration is planned in an industrial zone, characterized by relatively flat terrain with minimal elevation changes. The site is strategically located near major transportation routes, facilitating logistics for the resin sand casting operations. The project encompasses various structures, including mixing workshops, storage yards, cleaning facilities, and main production halls, all integral to the resin sand casting workflow. Given the industrial nature of resin sand casting, which involves high-precision equipment and substantial weights, the geotechnical conditions must be thoroughly assessed to prevent subsidence or structural failures.
To evaluate the site suitability for the resin sand casting project, we employed a combination of drilling, in-situ testing, and laboratory analyses. The investigation involved the deployment of two GXY-1 drilling rigs, utilizing impact drilling and rotary drilling with casing protection. A total of 30 boreholes were drilled, comprising 17 general boreholes and 13 control boreholes, with depths ranging from 9.30 to 24.30 meters. This approach ensured comprehensive coverage of the subsurface conditions relevant to the resin sand casting facility. In-situ tests included Standard Penetration Tests (SPT) and Heavy Dynamic Penetration Tests (HDPT), while laboratory tests involved routine soil analyses and groundwater quality assessments. The workload summary is presented in Table 1, highlighting the extensive efforts undertaken to characterize the site for the resin sand casting project.
| Item | Quantity | Remarks |
|---|---|---|
| Drilling (meters/holes) | 402.45/30 | Core sampling and logging |
| Water Samples (pieces) | 2 | For chemical analysis |
| Engineering Point Survey (points) | 30 | Topographic mapping |
| Heavy Dynamic Penetration (meters/holes) | 13.3/9 | In-situ strength testing |
| Disturbed Soil Samples (pieces) | 2 | For soluble salt analysis |
| Sand Samples (pieces) | 37 | For particle size distribution |
| Undisturbed Soil Samples (pieces) | 22 | For routine laboratory tests |
| Standard Penetration Tests (times/holes) | 60/21 | Soil density and consistency evaluation |
The subsurface conditions at the resin sand casting project site consist of Quaternary alluvial and proluvial deposits, including silt, coarse sand, medium sand, gravelly sand, rounded gravel, and silty clay. These layers were identified through drilling and are depicted in a geological profile. Each layer exhibits distinct characteristics that influence the foundation design for the resin sand casting structures. For instance, the silt layer is loose and moist, with limited bearing capacity, while the coarse sand layer is moderately dense and can serve as a suitable shallow foundation bearing stratum. The rounded gravel layer, being dense and saturated, offers higher load-bearing capacity, which is crucial for supporting the heavy loads of resin sand casting equipment. A detailed description of the soil layers is provided in Table 2, which summarizes their thickness, elevation, and engineering properties relevant to the resin sand casting project.
| Layer | Description | Thickness (m) | Elevation Range (m) | Engineering Remarks |
|---|---|---|---|---|
| ① Silt | Yellow-brown, loose, moist | 0.50–2.30 | 1067.71–1069.26 | Low bearing capacity, not suitable as direct bearing stratum |
| ② Coarse Sand | Gray-brown, moderately dense, moist | 0.20–3.30 | 1064.40–1068.86 | Suitable for shallow foundations in resin sand casting structures |
| ②-1 Medium Sand | Yellow-brown, loose, moist | 0.50–1.30 | 1066.38–1068.57 | Discontinuous lens, poor engineering performance |
| ③ Gravelly Sand | Variegated, moderately dense, wet | 0.60–2.80 | 1064.06–1067.22 | Moderate bearing capacity, variable distribution |
| ④ Rounded Gravel | Variegated, moderately dense, wet-saturated | 0.40–4.90 | 1061.06–1064.20 | High bearing capacity, ideal for deep foundations in resin sand casting |
| ⑤ Silty Clay | Brown, soft to fluid | Up to 15.30 | Below 1061.06 | High compressibility, not recommended as bearing layer |
Hydrogeological conditions play a pivotal role in the stability of the resin sand casting project. Groundwater exists as phreatic water within the rounded gravel layer, with a stable water level elevation ranging from 1061.72 to 1064.98 meters, corresponding to a depth of 5.0 to 8.0 meters below ground surface. The groundwater flow direction is from southwest to northeast, with an estimated average permeability coefficient of 45 m/d. This high permeability necessitates careful consideration during excavation and foundation construction for the resin sand casting facility. The groundwater quality was analyzed to assess its corrosivity, which is critical for the durability of concrete and reinforced concrete elements used in resin sand casting structures. The results, summarized in Table 3, indicate that both groundwater and soil have low corrosivity, minimizing the risk of structural degradation over time.
| Medium | pH | Chemical Ions (mg/L) | Corrosivity to Concrete | Corrosivity to Steel Reinforcement |
|---|---|---|---|---|
| Groundwater | 7.72–7.73 | Ca²⁺: 115–123, Mg²⁺: 48–50, Cl⁻: 67–71, SO₄²⁻: 212–228 | Micro-corrosive | Micro-corrosive |
| Soil | 7.71–7.72 | Ca²⁺: 118–132, Mg²⁺: 42–49, Cl⁻: 39–48, SO₄²⁻: 95–105 | Micro-corrosive | Micro-corrosive |
Seismic effects are a major concern for the resin sand casting project, given the region’s seismic activity. Based on the Chinese Code for Seismic Design of Buildings (GB 50011-2010), the site is located in an area with a seismic fortification intensity of 8 degrees, a design basic seismic acceleration of 0.30 g, and belongs to the second seismic design group. The site classification is Category II, indicating moderate soil stiffness. Liquefaction potential was evaluated using Standard Penetration Test data, and no liquefiable layers were identified, which is advantageous for the stability of resin sand casting structures during earthquakes. The seismic response can be analyzed using the following formula for peak ground acceleration (PGA):
$$ PGA = A_{max} \cdot F_s \cdot F_{site} $$
Where \( A_{max} \) is the maximum seismic acceleration (0.30 g for this resin sand casting site), \( F_s \) is a soil amplification factor (typically 1.2 for Category II sites), and \( F_{site} \) is a site coefficient. For the resin sand casting project, this yields a design PGA of approximately 0.36 g, which must be considered in structural calculations. Additionally, the seismic base shear coefficient \( C_s \) can be estimated as:
$$ C_s = \frac{S_{DS}}{R / I_e} $$
Here, \( S_{DS} \) is the design spectral acceleration (derived from site-specific parameters), \( R \) is the response modification factor (taken as 5 for industrial buildings like resin sand casting facilities), and \( I_e \) is the importance factor (1.0 for standard structures). These calculations ensure that the resin sand casting project meets seismic safety requirements.
The geotechnical engineering evaluation for the resin sand casting project involves assessing the bearing capacity and deformation characteristics of each soil layer. Based on in-situ test results and empirical correlations, the allowable bearing capacities and deformation moduli were determined, as shown in Table 4. These values are crucial for foundation design in resin sand casting, where equipment loads can be significant. For example, the coarse sand layer has an allowable bearing capacity of 145 kPa, making it suitable for shallow foundations, while the rounded gravel layer offers 200 kPa, ideal for heavier loads. The deformation moduli indicate the soil’s stiffness, which affects settlement predictions. The settlement \( S \) under a load \( q \) can be calculated using the formula:
$$ S = \frac{q \cdot B \cdot (1 – \nu^2)}{E_s} \cdot I_s $$
Where \( B \) is the foundation width, \( \nu \) is Poisson’s ratio (assumed as 0.3 for granular soils in resin sand casting sites), \( E_s \) is the deformation modulus from Table 4, and \( I_s \) is an influence factor depending on foundation shape. For the resin sand casting structures, this helps estimate potential settlements to ensure operational stability.
| Soil Layer | Allowable Bearing Capacity \( f_{ak} \) (kPa) | Deformation Modulus \( E_0 \) (MPa) | Compression Modulus \( E_s \) (MPa) for Fine Soils |
|---|---|---|---|
| ① Silt | 105 | 4.8 | 5.0 (estimated) |
| ② Coarse Sand | 145 | 10.0 | N/A |
| ②-1 Medium Sand | 130 | 7.8 | N/A |
| ③ Gravelly Sand | 180 | 15.6 | N/A |
| ④ Rounded Gravel | 200 | 16.4 | N/A |
| ⑤ Silty Clay | 110 | 5.15 | 5.15 |
For the resin sand casting project, foundation方案 selection is guided by the soil properties and structural requirements. Given the moderate bearing capacities and relatively shallow groundwater table, shallow foundations such as strip footings or isolated footings are recommended for most structures in the resin sand casting facility. These foundations can be constructed on the coarse sand layer after proper excavation and compaction. The design load \( Q \) for a footing can be verified using the ultimate bearing capacity formula:
$$ q_u = c’N_c + q’N_q + 0.5 \gamma B N_\gamma $$
Where \( c’ \) is the effective cohesion (negligible for granular soils in resin sand casting sites), \( q’ \) is the effective overburden pressure, \( \gamma \) is the soil unit weight, \( B \) is the footing width, and \( N_c, N_q, N_\gamma \) are bearing capacity factors dependent on the soil friction angle. For the coarse sand layer at the resin sand casting site, with an assumed friction angle of 30°, this yields a high ultimate capacity, ensuring safety factors above 3.0. For deeper or heavier structures in the resin sand casting process, such as the main production hall, piled foundations embedded in the rounded gravel layer may be considered to mitigate settlement risks.
Excavation for the resin sand casting project requires careful slope stability analysis. The proposed slope ratio of 1:0.5 is suitable for temporary excavations, but given the groundwater presence, dewatering measures might be necessary. The factor of safety \( FS \) against slope failure can be estimated using the infinite slope model:
$$ FS = \frac{c’ + (\gamma z \cos^2 \beta – u) \tan \phi’}{\gamma z \sin \beta \cos \beta} $$
Here, \( z \) is the depth of excavation, \( \beta \) is the slope angle, \( u \) is the pore water pressure, and \( \phi’ \) is the effective friction angle. For the resin sand casting site, with \( \gamma = 18 \, \text{kN/m}^3 \), \( z = 5 \, \text{m} \), and \( \phi’ = 28^\circ \) for silt, the \( FS \) exceeds 1.5 under drained conditions, indicating stability. However, during construction of the resin sand casting facility, monitoring of pore pressures is advised to prevent instability.
In conclusion, the site suitability assessment for the resin sand casting project reveals favorable geotechnical conditions. The absence of major不良 geological processes, low seismic liquefaction potential, and adequate bearing capacities support the feasibility of constructing a resin sand casting facility. The groundwater and soil corrosivity are minimal, reducing long-term maintenance costs for the resin sand casting structures. Based on this analysis, I recommend using shallow foundations for most buildings, with detailed design incorporating the seismic and settlement considerations outlined. Regular geotechnical monitoring during construction of the resin sand casting project is essential to address any unforeseen conditions. This comprehensive approach ensures that the resin sand casting operations will be built on a stable and safe foundation, contributing to the project’s success and sustainability.
Furthermore, the integration of advanced geotechnical modeling can enhance the design for the resin sand casting project. Finite element analysis (FEA) can simulate soil-structure interaction under dynamic loads, which is particularly relevant for resin sand casting equipment that may induce vibrations. The governing equation for FEA in geomechanics is:
$$ [K] \{u\} = \{F\} $$
Where \( [K] \) is the global stiffness matrix derived from soil parameters like \( E_0 \) and \( \nu \), \( \{u\} \) is the displacement vector, and \( \{F\} \) is the load vector from resin sand casting machinery. Such analyses help optimize foundation dimensions and reinforcement, ensuring resilience for the resin sand casting facility. Additionally, probabilistic methods can assess risks, accounting for uncertainties in soil properties at the resin sand casting site. The reliability index \( \beta \) can be calculated as:
$$ \beta = \frac{\mu_R – \mu_S}{\sqrt{\sigma_R^2 + \sigma_S^2}} $$
Here, \( \mu_R \) and \( \mu_S \) are the mean resistance and load, respectively, and \( \sigma_R \) and \( \sigma_S \) are their standard deviations. For the resin sand casting project, targeting \( \beta > 3.0 \) aligns with industry standards for safety.
Environmental considerations are also vital for the resin sand casting project. The site’s proximity to a river necessitates erosion control measures. The sediment transport rate \( Q_s \) can be estimated using the Engelund-Hansen formula:
$$ Q_s = 0.05 \cdot \gamma_s \cdot \sqrt{g d^3} \cdot \left( \frac{\tau}{\tau_c} – 1 \right)^{2.5} $$
Where \( \gamma_s \) is the sediment specific weight, \( g \) is gravity, \( d \) is sediment grain size, \( \tau \) is bed shear stress, and \( \tau_c \) is critical shear stress. For the resin sand casting site, implementing riprap or vegetative buffers can reduce erosion risks, protecting the foundation integrity. Moreover, the resin sand casting process may involve chemical usage, so containment systems should be designed to prevent soil and groundwater contamination, aligning with sustainable practices for resin sand casting industries.
In summary, this assessment underscores the importance of thorough geotechnical investigations for resin sand casting projects. By leveraging data from drilling, testing, and analysis, engineers can develop robust foundation solutions that accommodate the unique demands of resin sand casting operations. The repetitive mention of resin sand casting throughout this article highlights its centrality to the project’s geotechnical evaluation. As urbanization continues, such detailed assessments will remain crucial for ensuring the safety and efficiency of industrial developments like resin sand casting facilities. I hope this analysis provides a valuable reference for similar projects in the future, promoting best practices in geotechnical engineering for the resin sand casting sector and beyond.